please help ... thanks

For the sake of it!

(b)
[MATH] \begin{align}\\ |\sin^2 x - \sin^2 y| & = \frac{1}{2} |\cos 2y - \cos 2x|\\ & =|\sin(x+y)\sin(x-y)|\\ & ≤|x-y| \hspace5ex \text{ since } |\sin u|≤1 \text{ and } |\sin u|≤|u| \end{align}\\ [/MATH]
 
If we know that \(|f(x)|\le|x|^{\frac{3}{2}}[\forall x\in(-\infty,\infty)]\), what does that tell us about \(f(0)~?\)
Then is it the case that \(|f(0+h)-f(0)|=|(f(h)|\le|h|^{\frac{3}{2}}~?\)
To finish we need to know how the apply the \(\varepsilon/\delta\) definition of the derivative.
 
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