2023 ONE(b)

Achievement
Question
Find the rate of change of the function f(t)=t2e2tf(t)=t^2e^{2t} when t=1.5t=1.5.

You must use calculus and show any derivatives that you need to find when solving this problem.
Official Answer
f(t)=t2(2e2t)+e2t(2t)f'(t)=t^2(2e^{2t})+e^{2t}(2t)
=2t2e2t+2te2t=2t^2e^{2t}+2te^{2t}
=2te2t(t+1)=2te^{2t}(t+1)

f(1.5)=3e3(2.5)f'(1.5)=3e^3(2.5)
=7.5e3150.64=7.5e^3\approx 150.64
Grading Criteria

Achievement (u)

  • Correct derivative. AND Correct rate of change.

Merit (r)

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Excellence T1

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Excellence T2

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Video Explanation
2023 NCEA L3 Calculus Exam Walkthrough by infinityplusone(starts at 1:27)
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