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junior college 2 | H2 Maths
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Elle
Elle

junior college 2 chevron_right H2 Maths chevron_right Singapore

hello can anyone help me with this qns ? Thanks !!

Date Posted: 3 years ago
Views: 383

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Eric Nicholas K
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5997 answers (Tutor Details)
1st
I might be wrong because the workings are too short for a 7 mark question.
J
J
3 years ago
Elle : for c, as long as c < 0, you will always have two stationary points for this question.

y = ½x³ + cx

dy/dx = 3/2 x² + c

When dy/dx = 0, 3/2 x² + c = 0

x² = -2c/3

x² has to be positive in order to have two real roots (x² < 0 means imaginary/complex roots will be obtained, x² = 0 means only 1 real root of 0)


So for -2c/3 > 0, c < 0



As for the mark allocation,

4m → getting the general solution
3m → getting a particular solution and sketching the curve.

Not too little at all.
Elle
Elle
3 years ago
thankss