Christmas MT's answer to huihuibuhui's Junior College 1 H1 Maths Singapore question.

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Christmas MT
Christmas Mt's answer
3380 answers (A Helpful Person)
To do the first part, we first need to differentiate the equation with respect to t. Dx/dt would need to be >0 in order to be increasing with t. Hence, we complete the square and we recognise that the k value needs to be >48 for the dx/dt to be >0. The other parts can be solved using GC.