I don't know if there's anything missing or wrong with this question ... many th

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secondary 4 | E Maths
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I don't know if there's anything missing or wrong with this question ... many thanks for anyone who can guide me to the given answer of B) 800

Thank you !!!

Date Posted: 2 years ago

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Date Posted: 2 years ago

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The Learning Room

2 years ago

Thank you so much for your solution, Jeremy ! Really appreciate your time and help. :)

Just wondering if there's any way to solve this without using calculus ?

Jeremy

2 years ago

I have given my reply in the second answer. See if you can understand. The key is to know that there is a 'double root equation' -(m-10t)^2.

Double root equation does not cross the x axis (parameter t in this case) graphically. This means if we solely plot -(m-10t)^2..without the k, the top of the curve (or the maximum) touches P=0 at t=3. We make use of this fact (P=0 at t=3, for p=-(m-10t)^2 without the k) to find m.

From m, you can find k.