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Product, quotient and chain rulesAQA A-Level Maths: Flashcards

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State the chain rule.

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State the chain rule.
dydx=dydu×dudx\frac{dy}{dx}=\frac{dy}{du}\times\frac{du}{dx}
State the product rule.
ddx(uv)=udvdx+vdudx\frac{d}{dx}(uv)=u\frac{dv}{dx}+v\frac{du}{dx}
State the quotient rule.
ddx(uv)=vdudx−udvdxv2\frac{d}{dx}\left(\frac{u}{v}\right)=\frac{v\frac{du}{dx}-u\frac{dv}{dx}}{v^2}
Differentiate (2x+1)5(2x+1)^5.
10(2x+1)410(2x+1)^4
Differentiate x2e3xx^2e^{3x}.
(2x+3x2)e3x(2x+3x^2)e^{3x}
Differentiate xx2+1\frac{x}{x^2+1}.
(x2+1)−x(2x)(x2+1)2=1−x2(x2+1)2\frac{(x^2+1)-x(2x)}{(x^2+1)^2}=\frac{1-x^2}{(x^2+1)^2}
How are dydx\frac{dy}{dx} and dxdy\frac{dx}{dy} related?
dydx=1dxdy\frac{dy}{dx}=\frac{1}{\frac{dx}{dy}}
Connected rates: how do you find drdt\frac{dr}{dt} from dVdt\frac{dV}{dt} and V(r)V(r)?
drdt=dVdt÷dVdr\frac{dr}{dt}=\frac{dV}{dt}\div\frac{dV}{dr}
What is dVdr\frac{dV}{dr} for V=43πr3V=\frac43\pi r^3?
4πr24\pi r^2
In a connected rates question, when do you substitute numbers?
After differentiating, not before.
Differentiate ln⁡(x2+1)\ln(x^2+1).
2xx2+1\frac{2x}{x^2+1}, by the chain rule
Differentiate sin⁡2x\sin^2x.
2sin⁡xcos⁡x2\sin x\cos x, by the chain rule

Exam questions on Product, quotient and chain rules

  1. A curve has equation y=x2e3xy=x^2e^{3x}.
    Show that the stationary point at x=0x=0 is a minimum.2 marks
  2. A curve has equation y=3x+1x2+1y=\frac{3x+1}{x^2+1}.
    Find the xx-coordinates of the stationary points of the curve, correct to 3 significant figures.2 marks
  3. A curve has equation y=4x2+9y=\sqrt{4x^2+9}.
    Find dydx\frac{dy}{dx}, simplifying your answer.3 marks
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Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).