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VCE Math Methods calculus (differentiation and integration): The 2026 guide

Study guide22 min read

Quick answer

VCE Math Methods calculus is the most heavily examined area of the course, rewards by-hand fluency with the four differentiation rules and standard derivatives and antiderivatives on Paper 1, and rewards efficient CAS use plus disciplined optimisation and kinematics setup on Paper 2.

Jump to a section
  1. What calculus is really asking
  2. Differentiation
  3. Antidifferentiation and integration
  4. Applications
  5. Common Paper 1 calculus traps
  6. How calculus is examined
  7. Practice strategy
  8. Check your knowledge

What calculus is really asking

VCE Math Methods Area of Study 3 (Calculus) is the most heavily examined area of the course, accounting for roughly 35 percent of exam marks across the two papers. Calculus is also the most cumulative area, building on functions (AoS 1) and feeding into applications throughout Paper 2 Section B.

Calculus is examined in two flavours. Paper 1 (Tech-Free) tests by-hand differentiation and integration with exact-value trig and standard derivative rules. Paper 2 (Tech-Active, CAS) tests applications, modelling, optimisation, and kinematics where the CAS handles the algebra and you handle the interpretation.

Strong calculus students cap their study scores in the mid-40s. Weak calculus students cap in the mid-30s.

Differentiation

From first principles

The definition of the derivative:

f′(x)=lim⁡h→0f(x+h)−f(x)hf'(x) = \lim_{h \to 0} \frac{f(x + h) - f(x)}{h}

VCAA examines first-principles differentiation at least once per cycle, usually on Paper 1, for a simple polynomial.

Differentiate f(x)=x2+3xf(x) = x^2 + 3x from first principles

Step 1. Write the definition. Apply the limit definition so every method mark is visible.

f′(x)=lim⁡h→0f(x+h)−f(x)hf'(x) = \lim_{h \to 0} \frac{f(x + h) - f(x)}{h}

Step 2. Expand f(x+h)f(x + h). Substitute (x+h)(x+h) wherever xx appears in the rule.

f(x+h)=(x+h)2+3(x+h)=x2+2xh+h2+3x+3hf(x + h) = (x + h)^2 + 3(x + h) = x^2 + 2xh + h^2 + 3x + 3h

Step 3. Form the numerator f(x+h)−f(x)f(x + h) - f(x). Cancel the x2x^2 and 3x3x terms so the numerator divides cleanly by hh.

f(x+h)−f(x)=2xh+h2+3hf(x + h) - f(x) = 2xh + h^2 + 3h

Step 4. Divide by hh. This step is the whole point of first principles.

f(x+h)−f(x)h=2x+h+3\frac{f(x + h) - f(x)}{h} = 2x + h + 3

Step 5. Take the limit as h→0h \to 0. Substitute h=0h = 0 since the expression is now continuous in hh.

f′(x)=lim⁡h→0(2x+h+3)=2x+3f'(x) = \lim_{h \to 0} (2x + h + 3) = 2x + 3

Answer. f′(x)=2x+3f'(x) = 2x + 3.

The four rules

Sum rule
ddx[f(x)+g(x)]=f′(x)+g′(x)\frac{d}{dx}[f(x) + g(x)] = f'(x) + g'(x)
Product rule
ddx[f(x)⋅g(x)]=f′(x)g(x)+f(x)g′(x)\frac{d}{dx}[f(x) \cdot g(x)] = f'(x)g(x) + f(x)g'(x)
Quotient rule
ddx[f(x)g(x)]=f′(x)g(x)−f(x)g′(x)[g(x)]2\frac{d}{dx}\left[\frac{f(x)}{g(x)}\right] = \frac{f'(x)g(x) - f(x)g'(x)}{[g(x)]^2}
Chain rule
ddx[f(g(x))]=f′(g(x))⋅g′(x)\frac{d}{dx}[f(g(x))] = f'(g(x)) \cdot g'(x)

Standard derivatives (memorise)

  • ddx(xn)=nxn−1\frac{d}{dx}(x^n) = nx^{n-1}
  • ddx(ex)=ex\frac{d}{dx}(e^x) = e^x
  • ddx(ekx)=kekx\frac{d}{dx}(e^{kx}) = ke^{kx}
  • ddx(ln⁡x)=1x\frac{d}{dx}(\ln x) = \frac{1}{x}
  • ddx(sin⁡x)=cos⁡x\frac{d}{dx}(\sin x) = \cos x
  • ddx(cos⁡x)=−sin⁡x\frac{d}{dx}(\cos x) = -\sin x
  • ddx(tan⁡x)=sec⁡2x=1cos⁡2x\frac{d}{dx}(\tan x) = \sec^2 x = \frac{1}{\cos^2 x}
Differentiate f(x)=x2e3xf(x) = x^2 e^{3x} (Tech-Free, product rule)

Step 1. Identify the two factors. The product rule requires uu and vv with their derivatives.

Let u=x2u = x^2 and v=e3xv = e^{3x}.

Step 2. Differentiate each factor. Use the power rule for uu and the chain rule for vv.

u′=2x,v′=3e3xu' = 2x, \qquad v' = 3e^{3x}

Step 3. Apply the product rule f′(x)=u′v+uv′f'(x) = u'v + uv'. Substitute the four pieces directly.

f′(x)=2x⋅e3x+x2⋅3e3xf'(x) = 2x \cdot e^{3x} + x^2 \cdot 3e^{3x}

Step 4. Factorise. VCAA marking guides reward a factored final form because it makes stationary points easier to read.

f′(x)=e3x(2x+3x2)=xe3x(2+3x)f'(x) = e^{3x}(2x + 3x^2) = x e^{3x}(2 + 3x)

Answer. f′(x)=xe3x(2+3x)f'(x) = x e^{3x}(2 + 3x).

Differentiate h(x)=sin⁡(cos⁡(2x))h(x) = \sin(\cos(2x)) (chain rule on a composite of three)

Step 1. Name the three layers from outside in. Identifying layers stops sign errors creeping in.

The outer function is sin⁡(⋅)\sin(\cdot), the middle function is cos⁡(⋅)\cos(\cdot), and the inner function is 2x2x.

Step 2. Differentiate the outer layer, keeping its argument intact. The outer derivative is evaluated at the middle expression.

ddxsin⁡(cos⁡(2x))=cos⁡(cos⁡(2x))⋅ddx[cos⁡(2x)]\frac{d}{dx}\sin(\cos(2x)) = \cos(\cos(2x)) \cdot \frac{d}{dx}[\cos(2x)]

Step 3. Differentiate the middle layer, keeping the inner argument intact.

ddxcos⁡(2x)=−sin⁡(2x)⋅ddx(2x)=−2sin⁡(2x)\frac{d}{dx}\cos(2x) = -\sin(2x) \cdot \frac{d}{dx}(2x) = -2\sin(2x)

Step 4. Combine. Multiply the two derivatives, watching the negative sign from the cosine derivative.

h′(x)=cos⁡(cos⁡(2x))⋅(−2sin⁡(2x))=−2sin⁡(2x)cos⁡(cos⁡(2x))h'(x) = \cos(\cos(2x)) \cdot (-2\sin(2x)) = -2\sin(2x)\cos(\cos(2x))

Answer. h′(x)=−2sin⁡(2x)cos⁡(cos⁡(2x))h'(x) = -2\sin(2x)\cos(\cos(2x)).

Stationary points and the second derivative

A stationary point is where f′(x)=0f'(x) = 0. Classification.

  • Local minimum. f′′(x)>0f''(x) > 0 at the stationary point (concave up).
  • Local maximum. f′′(x)<0f''(x) < 0 (concave down).
  • Stationary point of inflection. f′′(x)=0f''(x) = 0 AND the sign of f′f' does not change either side.

A point of inflection (not necessarily stationary) is where f′′(x)=0f''(x) = 0 AND f′′f'' changes sign.

Classify the stationary points of f(x)=x3−3x2+4f(x) = x^3 - 3x^2 + 4 (Tech-Free)

Step 1. Differentiate. Use the power rule term by term.

f′(x)=3x2−6x=3x(x−2)f'(x) = 3x^2 - 6x = 3x(x - 2)

Step 2. Solve f′(x)=0f'(x) = 0. Factor and set each factor to zero so both stationary x-values are visible.

3x(x−2)=0  ⟹  x=0 or x=23x(x - 2) = 0 \implies x = 0 \text{ or } x = 2

Step 3. Compute the second derivative. A sign on f′′f'' at each stationary point classifies it without a sign-line.

f′′(x)=6x−6f''(x) = 6x - 6

Step 4. Test each stationary point. Substitute each x-value into f′′f''.

f′′(0)=−6<0f''(0) = -6 < 0, so x=0x = 0 is a local maximum. f′′(2)=6>0f''(2) = 6 > 0, so x=2x = 2 is a local minimum.

Step 5. Find the y-coordinates. Substitute back into ff to give the full coordinates.

f(0)=4f(0) = 4 and f(2)=8−12+4=0f(2) = 8 - 12 + 4 = 0.

Answer. Local max at (0,4)(0, 4), local min at (2,0)(2, 0).

Antidifferentiation and integration

Standard antiderivatives (memorise)

  • ∫xn dx=xn+1n+1+c\int x^n\,dx = \frac{x^{n+1}}{n+1} + c for n≠−1n \neq -1
  • ∫1x dx=ln⁡∣x∣+c\int \frac{1}{x}\,dx = \ln|x| + c
  • ∫ex dx=ex+c\int e^x\,dx = e^x + c
  • ∫ekx dx=1kekx+c\int e^{kx}\,dx = \frac{1}{k}e^{kx} + c
  • ∫sin⁡x dx=−cos⁡x+c\int \sin x\,dx = -\cos x + c
  • ∫cos⁡x dx=sin⁡x+c\int \cos x\,dx = \sin x + c
  • ∫sec⁡2x dx=tan⁡x+c\int \sec^2 x\,dx = \tan x + c

Definite integrals

By the Fundamental Theorem of Calculus:

∫abf(x) dx=F(b)−F(a)\int_a^b f(x)\,dx = F(b) - F(a)

where F′(x)=f(x)F'(x) = f(x).

The definite integral represents the signed area between the curve and the x-axis on [a,b][a, b]. Area below the x-axis contributes negatively.

For the total area between the curve and the x-axis (a common Paper 2 question):

A=∫ac∣f(x)∣ dxA = \int_a^c |f(x)|\,dx

In practice, find the x-intercepts, then integrate each section separately taking absolute values.

Evaluate ∫0π/2cos⁡(2x) dx\int_0^{\pi/2} \cos(2x)\,dx (Tech-Free)

Step 1. Find the antiderivative. Use the reverse-chain factor 1/k1/k for cos⁡(kx)\cos(kx).

∫cos⁡(2x) dx=12sin⁡(2x)+c\int \cos(2x)\,dx = \frac{1}{2}\sin(2x) + c

Step 2. Apply the Fundamental Theorem of Calculus. Substitute the upper limit, then the lower, and subtract.

∫0π/2cos⁡(2x) dx=[12sin⁡(2x)]0π/2\int_0^{\pi/2} \cos(2x)\,dx = \left[\frac{1}{2}\sin(2x)\right]_0^{\pi/2}

Step 3. Evaluate. Use exact values sin⁡(π)=0\sin(\pi) = 0 and sin⁡(0)=0\sin(0) = 0.

12sin⁡(π)−12sin⁡(0)=0−0=0\frac{1}{2}\sin(\pi) - \frac{1}{2}\sin(0) = 0 - 0 = 0

Answer. ∫0π/2cos⁡(2x) dx=0\int_0^{\pi/2} \cos(2x)\,dx = 0. The integrand is positive on [0,π/4][0, \pi/4] and equally negative on [π/4,π/2][\pi/4, \pi/2], so the signed area cancels.

Find ∫2xx2+5 dx\int \frac{2x}{x^2 + 5}\,dx by recognition (Tech-Free)

Step 1. Recognise the structure. The numerator is the derivative of the denominator. That signals an ln⁡\ln antiderivative because ddxln⁡∣g(x)∣=g′(x)g(x)\frac{d}{dx}\ln|g(x)| = \frac{g'(x)}{g(x)}.

Here g(x)=x2+5g(x) = x^2 + 5 and g′(x)=2xg'(x) = 2x.

Step 2. State the standard form. Pattern match against ∫g′(x)g(x) dx=ln⁡∣g(x)∣+c\int \frac{g'(x)}{g(x)}\,dx = \ln|g(x)| + c.

∫2xx2+5 dx=ln⁡∣x2+5∣+c\int \frac{2x}{x^2 + 5}\,dx = \ln|x^2 + 5| + c

Step 3. Drop the absolute value if possible. Since x2+5>0x^2 + 5 > 0 for all real xx, the absolute value is unnecessary.

∫2xx2+5 dx=ln⁡(x2+5)+c\int \frac{2x}{x^2 + 5}\,dx = \ln(x^2 + 5) + c

Answer. ln⁡(x2+5)+c\ln(x^2 + 5) + c.

Find the area enclosed by y=x2y = x^2 and y=2xy = 2x (Tech-Free, area between curves)

Step 1. Find the intersection points. Set the two curves equal so the region's left and right limits are exact.

x2=2x  ⟹  x2−2x=0  ⟹  x(x−2)=0  ⟹  x=0 or x=2x^2 = 2x \implies x^2 - 2x = 0 \implies x(x - 2) = 0 \implies x = 0 \text{ or } x = 2

Step 2. Decide which curve is on top. Test a midpoint such as x=1x = 1.

At x=1x = 1: y=x2y = x^2 gives 11, while y=2xy = 2x gives 22. So y=2xy = 2x is on top on [0,2][0, 2].

Step 3. Set up the area integral. Subtract the lower curve from the upper across the interval of intersection.

A=∫02(2x−x2) dxA = \int_0^2 (2x - x^2)\,dx

Step 4. Integrate term by term.

∫(2x−x2) dx=x2−x33+c\int (2x - x^2)\,dx = x^2 - \frac{x^3}{3} + c

Step 5. Evaluate the definite integral. Substitute the limits.

A=[x2−x33]02=(4−83)−0=12−83=43A = \left[x^2 - \frac{x^3}{3}\right]_0^2 = \left(4 - \frac{8}{3}\right) - 0 = \frac{12 - 8}{3} = \frac{4}{3}

Answer. The enclosed area is 43\frac{4}{3} square units.

Applications

Kinematics

The standard variables for a particle moving in a straight line.

  • Position (also called displacement from origin), x(t)x(t).
  • Velocity, v(t)=x′(t)=dxdtv(t) = x'(t) = \frac{dx}{dt}.
  • Acceleration, a(t)=v′(t)=x′′(t)a(t) = v'(t) = x''(t).

Going forward (position to velocity to acceleration) uses differentiation. Going backward (acceleration to velocity to position) uses antidifferentiation with initial conditions to find the constants.

Distance versus displacement. Displacement is the signed change in position. Distance is the total path length, accounting for direction changes. If a particle moves 5m right then 3m left, displacement is +2+2m and distance is 88m.

Particle with a(t)=6t−4a(t) = 6t - 4, v(0)=−2v(0) = -2, x(0)=1x(0) = 1. Find x(t)x(t) (Tech-Free, kinematics)

Step 1. Integrate acceleration to get velocity. Antidifferentiation with a constant of integration c1c_1.

v(t)=∫(6t−4) dt=3t2−4t+c1v(t) = \int (6t - 4)\,dt = 3t^2 - 4t + c_1

Step 2. Use the initial velocity to find c1c_1. Substitute t=0t = 0 and v(0)=−2v(0) = -2.

v(0)=0−0+c1=−2  ⟹  c1=−2v(0) = 0 - 0 + c_1 = -2 \implies c_1 = -2

So v(t)=3t2−4t−2v(t) = 3t^2 - 4t - 2.

Step 3. Integrate velocity to get position. A second constant c2c_2 appears.

x(t)=∫(3t2−4t−2) dt=t3−2t2−2t+c2x(t) = \int (3t^2 - 4t - 2)\,dt = t^3 - 2t^2 - 2t + c_2

Step 4. Use the initial position to find c2c_2. Substitute t=0t = 0 and x(0)=1x(0) = 1.

x(0)=0−0−0+c2=1  ⟹  c2=1x(0) = 0 - 0 - 0 + c_2 = 1 \implies c_2 = 1

Answer. x(t)=t3−2t2−2t+1x(t) = t^3 - 2t^2 - 2t + 1.

Optimisation

The standard six-step recipe.

  1. Read the problem and identify the quantity to be optimised (volume, area, cost, profit).
  2. Express the quantity in terms of one variable using any constraint(s).
  3. Differentiate.
  4. Set the derivative to zero and solve for the stationary point(s).
  5. Classify the stationary point as max or min using the second derivative or sign analysis.
  6. Check the endpoints of the domain if it is restricted. The global max or min may be at an endpoint, not at a stationary point.
Minimise the surface area of a 1-litre cylindrical can (Tech-Active, optimisation)

Step 1. Write the quantity to optimise and the constraint. Surface area A=2πr2+2πrhA = 2\pi r^2 + 2\pi r h and the volume constraint πr2h=1000\pi r^2 h = 1000 cm³ (since 1 litre is 1000 cm³).

Step 2. Reduce to one variable. Solve the constraint for hh and substitute.

h=1000πr2h = \frac{1000}{\pi r^2}

A(r)=2πr2+2πr⋅1000πr2=2πr2+2000rA(r) = 2\pi r^2 + 2\pi r \cdot \frac{1000}{\pi r^2} = 2\pi r^2 + \frac{2000}{r}

Step 3. Differentiate. Rewrite the second term as 2000r−12000 r^{-1} for the power rule.

A′(r)=4πr−2000r2A'(r) = 4\pi r - \frac{2000}{r^2}

Step 4. Solve A′(r)=0A'(r) = 0. Set the derivative to zero and multiply through by r2r^2.

4πr3=2000  ⟹  r3=500π  ⟹  r=(500π)1/3≈5.42 cm4\pi r^3 = 2000 \implies r^3 = \frac{500}{\pi} \implies r = \left(\frac{500}{\pi}\right)^{1/3} \approx 5.42 \text{ cm}

Step 5. Classify with the second derivative.

A′′(r)=4π+4000r3>0 for all r>0A''(r) = 4\pi + \frac{4000}{r^3} > 0 \text{ for all } r > 0

So this is a minimum.

Step 6. State the matching hh with units. Substitute the optimal rr back into the constraint.

h=1000π(5.42)2≈10.84 cmh = \frac{1000}{\pi (5.42)^2} \approx 10.84 \text{ cm}

Notice h=2rh = 2r at the minimum, a standard result for the optimised cylinder.

Answer. The can is minimised when r≈5.42r \approx 5.42 cm and h≈10.84h \approx 10.84 cm.

Common Paper 1 calculus traps

Chain rule errors on ef(x)e^{f(x)}
ddx(e3x2)=6x⋅e3x2\frac{d}{dx}(e^{3x^2}) = 6x \cdot e^{3x^2}, not just e3x2e^{3x^2} or 6xe6x6x e^{6x}. Always identify the inner function and apply the chain rule.
Missing the constant of integration
Indefinite integrals require +c+ c. Definite integrals do not. Losing cc in an indefinite integral is a routine 1-mark penalty.
Sign error in ∫sin⁡\int \sin versus ∫cos⁡\int \cos
∫sin⁡x dx=−cos⁡x+c\int \sin x\,dx = -\cos x + c. Memorise this with the negative sign.
Forgetting to use absolute area for total distance or area
If asked for total distance (or total area enclosed), set up the integrand as ∣v(t)∣|v(t)| or ∣f(x)∣|f(x)| and integrate piecewise.
Endpoint neglect in optimisation
Always check the endpoints of the domain. The minimum cost or maximum volume might occur at the boundary, not at a stationary point.

How calculus is examined

In the VCE Math Methods exams:

  • Paper 1 (Tech-Free). Roughly 15-18 marks. Standard patterns include first-principles differentiation, apply product/quotient/chain rule to a complex function, evaluate a definite integral exactly, find a tangent line, set up an antiderivative with initial conditions.
  • Paper 2 Section A (Tech-Active, multiple choice). 4-6 multiple-choice questions including stationary point classification, signed area, average rate of change.
  • Paper 2 Section B (Tech-Active, extended response). Major modelling question almost always includes calculus. Common patterns: a function describes a curve (a hill, a river, a population), find the maximum or minimum, find the area between curves, find the average value over an interval.

Practice strategy

For VCE Math Methods calculus:

  • Term 1 and 2 of Year 12. Memorise the rules and standard derivatives and antiderivatives. Drill 20-30 routine differentiation and integration questions per week.
  • Term 3. Tackle optimisation and kinematics. These are SAC content and Paper 2 Section B content.
  • Term 4. Past VCAA Exam 1 papers under timed conditions. Score yourself separately on the calculus questions to identify gaps. The patterns repeat year to year.

See our VCE Math Methods practice questions for prompts modelled on VCAA past papers.

Check your knowledge

Eight questions, increasing in difficulty. Mark each as Tech-Free (Paper 1 style, by hand) or Tech-Active (Paper 2 style, CAS-permitted) and attempt them in those conditions.

Tech-Free (Paper 1 style)

  1. Differentiate f(x)=5x4−2x+xf(x) = 5x^4 - 2x + \sqrt{x}.
  2. Differentiate g(x)=(3x+1)e−2xg(x) = (3x + 1)e^{-2x} using the product rule.
  3. Evaluate ∫1e1x dx\int_1^e \frac{1}{x}\,dx exactly.
  4. Find the equation of the tangent to y=x3−4xy = x^3 - 4x at x=1x = 1.
  5. Find ∫(2sin⁡(3x)+e−x) dx\int (2\sin(3x) + e^{-x})\,dx.

Tech-Active (Paper 2 style)

  1. The position of a particle is x(t)=t3−6t2+9tx(t) = t^3 - 6t^2 + 9t for t≥0t \geq 0, in metres. Find the total distance travelled in the first 4 seconds.
  2. Find the area enclosed between y=4−x2y = 4 - x^2 and y=x+2y = x + 2.
  3. A rectangle has its base on the x-axis and its upper two vertices on the curve y=8−x2y = 8 - x^2. Find the dimensions that maximise the rectangle's area.
Solutions to check-your-knowledge questions

These eight questions cover power-rule differentiation, the product rule, definite integrals of 1/x1/x, tangent lines, antidifferentiation of trig and exponential terms, total distance from velocity, area between curves, and optimisation of a rectangle inscribed under a parabola.

Step 1: Q1. Differentiate f(x)=5x4−2x+xf(x) = 5x^4 - 2x + \sqrt{x}

Rewrite x=x1/2\sqrt{x} = x^{1/2} so every term is a power of xx, then differentiate term by term using the power rule.

f′(x)=20x3−2+12x−1/2=20x3−2+12xf'(x) = 20x^3 - 2 + \frac{1}{2}x^{-1/2} = 20x^3 - 2 + \frac{1}{2\sqrt{x}}

Step 2: Q2. Differentiate g(x)=(3x+1)e−2xg(x) = (3x + 1)e^{-2x} using the product rule

Let u=3x+1u = 3x + 1 and v=e−2xv = e^{-2x}, so u′=3u' = 3 and v′=−2e−2xv' = -2e^{-2x}. Apply g′(x)=u′v+uv′g'(x) = u'v + uv' then factorise.

g′(x)=3e−2x+(3x+1)(−2e−2x)=e−2x(3−6x−2)=e−2x(1−6x)g'(x) = 3e^{-2x} + (3x + 1)(-2e^{-2x}) = e^{-2x}(3 - 6x - 2) = e^{-2x}(1 - 6x)

Step 3: Q3. Evaluate ∫1e1x dx\displaystyle\int_1^e \frac{1}{x}\,dx

The antiderivative of 1x\frac{1}{x} is ln⁡∣x∣\ln|x|. Apply the fundamental theorem, noting that ln⁡e=1\ln e = 1 and ln⁡1=0\ln 1 = 0.

∫1e1x dx=[ln⁡∣x∣]1e=ln⁡e−ln⁡1=1−0=1\int_1^e \frac{1}{x}\,dx = [\ln|x|]_1^e = \ln e - \ln 1 = 1 - 0 = 1

Step 4: Q4. Find the equation of the tangent to y=x3−4xy = x^3 - 4x at x=1x = 1

The gradient of the tangent equals y′y' evaluated at the point. Find the point on the curve first, then use point-gradient form.

y′(x)=3x2−4,y′(1)=−1(gradient)y'(x) = 3x^2 - 4, \quad y'(1) = -1 \quad \text{(gradient)}

y(1)=1−4=−3,so the point is (1,−3)y(1) = 1 - 4 = -3, \quad \text{so the point is } (1, -3)

y+3=−1(x−1)  ⟹  y=−x−2y + 3 = -1(x - 1) \implies y = -x - 2

Step 5: Q5. Antidifferentiate 2sin⁡(3x)+e−x2\sin(3x) + e^{-x}

Apply the reverse-chain factor to each term. For sin⁡(3x)\sin(3x) the inner derivative is 33, so divide by 33; for e−xe^{-x} the inner derivative is −1-1, so divide by −1-1.

∫2sin⁡(3x) dx=−23cos⁡(3x)+c,∫e−x dx=−e−x+c\int 2\sin(3x)\,dx = -\frac{2}{3}\cos(3x) + c, \qquad \int e^{-x}\,dx = -e^{-x} + c

Combined antiderivative: −23cos⁡(3x)−e−x+c-\dfrac{2}{3}\cos(3x) - e^{-x} + c.

Step 6: Q6. Total distance travelled by a particle with x(t)=t3−6t2+9tx(t) = t^3 - 6t^2 + 9t

The particle reverses direction where v(t)=0v(t) = 0. Find those times, evaluate position at each turning point and the endpoints, then add the absolute distances between consecutive positions.

v(t)=3t2−12t+9=3(t−1)(t−3)=0  ⟹  t=1, t=3v(t) = 3t^2 - 12t + 9 = 3(t - 1)(t - 3) = 0 \implies t = 1,\ t = 3

Positions: x(0)=0x(0) = 0, x(1)=4x(1) = 4, x(3)=0x(3) = 0, x(4)=4x(4) = 4.

Total distance=∣4−0∣+∣0−4∣+∣4−0∣=4+4+4=12 metres\text{Total distance} = |4 - 0| + |0 - 4| + |4 - 0| = 4 + 4 + 4 = 12 \text{ metres}

Step 7: Q7. Area between y=4−x2y = 4 - x^2 and y=x+2y = x + 2

Find the intersection points by equating the two expressions, then integrate (top minus bottom) over the interval where the parabola lies above the line.

4−x2=x+2  ⟹  x2+x−2=0  ⟹  (x+2)(x−1)=0  ⟹  x=−2, 14 - x^2 = x + 2 \implies x^2 + x - 2 = 0 \implies (x + 2)(x - 1) = 0 \implies x = -2,\ 1

A=∫−21(2−x−x2) dx=[2x−x22−x33]−21=76+206=276=92 square unitsA = \int_{-2}^{1} (2 - x - x^2)\,dx = \left[2x - \frac{x^2}{2} - \frac{x^3}{3}\right]_{-2}^{1} = \frac{7}{6} + \frac{20}{6} = \frac{27}{6} = \frac{9}{2} \text{ square units}

Step 8: Q8. Maximum area of a rectangle inscribed under y=8−x2y = 8 - x^2

Place the upper-right vertex at (x,8−x2)(x, 8 - x^2) with 0<x<220 < x < 2\sqrt{2}. The rectangle has width 2x2x and height 8−x28 - x^2. Differentiate the area function and set it to zero.

A(x)=2x(8−x2)=16x−2x3  ⟹  A′(x)=16−6x2=0  ⟹  x2=83, x=223A(x) = 2x(8 - x^2) = 16x - 2x^3 \implies A'(x) = 16 - 6x^2 = 0 \implies x^2 = \frac{8}{3},\ x = 2\sqrt{\frac{2}{3}}

Height: 8−83=1638 - \frac{8}{3} = \frac{16}{3}. Width: 4234\sqrt{\frac{2}{3}}.

Final answer: maximum area =6469= \dfrac{64\sqrt{6}}{9} square units (approximately 17.4217.42 square units).

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