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VCE Stuff => VCE Mathematics => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Mathematical Methods CAS => Topic started by: wildareal on July 03, 2010, 09:16:20 pm

Title: Related Rates Change
Post by: wildareal on July 03, 2010, 09:16:20 pm: If y=3x+2cosx, find dy/dx and hence show that y increases as x increases.
Title: Re: Related Rates Change
Post by: moekamo on July 03, 2010, 09:20:37 pm: $\frac{dy}{dx} = 3-2\sin x$ and since $\sin x \in [-1, 1] \implies 2\sin x \in [-2, 2] \implies 3-2\sin x \in [1, 5]$

therefore since dy/dx is always greater than 0, gradient of y is always positive hence y increases with x.