2015 TWO(b)

Achievement
Question
Find the gradient of the normal to the curve y=x−16xy = x - \dfrac{16}{x} at the point where x=4x = 4.

*You must use calculus and show any derivatives that you need to find when solving this
problem.*
Official Answer
dydx=1+16x2\dfrac{dy}{dx}=1+\dfrac{16}{x^2}

At x=4x=4, dydx=2\dfrac{dy}{dx}=2

∴\therefore Gradient of normal =−12=-\dfrac{1}{2}
Grading Criteria

Achievement (u)

  • Correct solution with correct derivative.

Merit (r)

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Excellence T1

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Excellence T2

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Exam Paper (2015)Assessment Schedule (2015)
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