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secondary 4 | E Maths
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secondary 4 chevron_right E Maths chevron_right Singapore

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: 1 year ago
Views: 328

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Jeremy
Jeremy's answer
6 answers (Tutor Details)
1st
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The Learning Room
The Learning Room
1 year 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
1 year 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.
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Jeremy
Jeremy's answer
6 answers (Tutor Details)
You need to recognise that there is a double root equation
The Learning Room
The Learning Room
1 year ago
Yes, thank you so much, Jeremy.