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secondary 4 | A Maths
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Jesse
Jesse

secondary 4 chevron_right A Maths chevron_right Singapore

Is it correct?

Date Posted: 1 day ago
Views: 17
Eric Nicholas K
Eric Nicholas K
1 day ago
My recommendation is to let e^x become a variable like "u" and convert the equation into a quadratic equation in u, like what you did in the cancelled workings.

The dy/dx path is going on an incorrect track in my opinion since dy/dx = 0 simply tells us to find the turning points.
Eric Nicholas K
Eric Nicholas K
1 day ago
Proceed on from your cancelled workings, but do not calculate the discriminant at all. The discriminant itself is going on an incorrect track.

3a² + 5a - 2 = 0
(3a + 1) (a - 2) = 0

a = -1/3, a = 2

e^x = -1/3, e^x = 2

We know that any positive number, raised to any real power, will be positive and can therefore not equal -1/3.

We will only have one solution arising from e^x = 2, and that is x = ln 2 = 0.69314... ~ 0.69.