Answer
(a) $dy$ = $-\frac{4x}{(x^{2}-3)^{3}}dx$
(b) $dy$ = $-\frac{2t^{3}}{\sqrt {1-t^{4}}}dt$
Work Step by Step
(a)
$\frac{dy}{dx}$ = $-2(x^{2}-3)^{-3}(2x)$
$dy$ = $-\frac{4x}{(x^{2}-3)^{3}}dx$
(b)
$\frac{dy}{dt}$ = $\frac{1}{2}(1-t^{4})^{-\frac{1}{2}}(-4t^{3})$
$dy$ = $-\frac{2t^{3}}{\sqrt {1-t^{4}}}dt$