Cрочно, только выделенные

2.
$\lim_{x \to \infty} ( \frac{2}{x^2}+ \frac{3}{x}-1)* \frac{7x^2-4}{2x^2+3}= \\ \\ = \lim_{x \to \infty} ( \frac{2}{x^2}+ \frac{3}{x}-1 )* \lim_{x \to \infty} \frac{7x^2-4}{2x^2+3}= \\ \\ =-1* \lim_{x \to \infty} \frac{ \frac{7x^2}{x^2}- \frac{4}{x^2} }{ \frac{2x^2}{x^2}+ \frac{3}{x^2} }=-1* \lim_{x \to \infty} \frac{7- \frac{4}{x^2} }{2+ \frac{3}{x^2} }= \\ \\ =-1* \frac{7}{2}=-3.5$

5.
a)
$g=( \frac{2}{x}-1 )cosx \\ \\ g'=( \frac{2}{x}-1 )'cosx+( \frac{2}{x}-1 )(cosx)'= \\ \\ =( -\frac{2}{x^2} )cosx-( \frac{2}{x}-1 )sinx= \\ \\ =- \frac{2cosx}{x^2}- \frac{2sinx}{x}+sinx= \frac{x^2sinx-2cosx-2xsinx}{x^2}$

6.
$y= \frac{( \sqrt{x} -3)sinx}{x^2}=x^{-2}( \sqrt{x} -3)sinx= \\ \\ =(x^{-2} \sqrt{x} -3x^{-2})sinx=(x^{-2+0.5}-3x^{-2})sinx= \\ \\ =(x^{-1.5}-3x^{-2})sinx$

$y'=(x^{-1.5}-3x^{-2})'sinx+(x^{-1.5}-3x^{-2})(sinx)'= \\ \\ =(-1.5x^{-2.5}+6x^{-3})sinx-(x^{-1.5}-3x^{-2})cosx= \\ \\ =(- \frac{3}{2x^2 \sqrt{x} }+ \frac{6}{x^3} )sinx-( \frac{1}{x \sqrt{x} }- \frac{3}{x^2} )cosx= \\ \\ =( \frac{6}{x^3}- \frac{3 \sqrt{x} }{2x^3} )sinx-( \frac{ \sqrt{x} -3}{x^2} )cosx= \\ \\ =( \frac{12-3 \sqrt{x} }{2x^3} )sinx-( \frac{ \sqrt{x} -3}{x^2} )cosx$