Jeremy's answer to The Learning Room's Secondary 4 E Maths Singapore question.

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Jeremy
Jeremy's answer
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The Learning Room
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
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.