Eric Nicholas K's answer to Janet's Junior College 1 H2 Maths Singapore question.

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Eric Nicholas K
Eric Nicholas K's answer
5997 answers (Tutor Details)
Q7b, Q9a

These are the alternative workings for Q7b by direct differentiation.

Q9a requires you to use chain rule for differentiation with respect to x. Since y is a function of x, it also gets differentiated to dy/dx (implicitly, which arises from the chain rule).

Q9b also requires a similar idea, which I will post next.