Question

помогите номер 13
второй и третий

Answer 1

1.
$.......= frac{a+a+1}{a+1} * frac{1+a}{2a+1}= frac{2a+1}{a+1}* frac{1+a}{2a+1}=1$

2.
..........=$( frac{m}{n^{2}}- frac{1}{m} ):( frac{1}{n}+ frac{1}{m})= frac{m^{2}-n^{2} }{n ^{2}m } * frac{nm}{m+n}= frac{(m-n)(m+n)}{n^{2}m }* frac{nm}{m+n}= frac{m-n}{n}$

3.
........................=$frac{b-2}{b-3} *(b+ frac{b}{2-b})= frac{b-2}{b-3}* frac{2b-b^{2}+b }{2-b}= frac{b-2}{b-3} * frac{b(3-b)}{2-b}= -frac{2-b}{3-b}* frac{b(3-b)}{2-b}=-b$
4.
..................=$(frac{4x}{2-x}-x): frac{x+2}{x-2}= frac{4x-2x+ x^{2} }{2-x} * frac{x-2}{x+2} = frac{x(2+x)}{2-x}* frac{x-2}{x+2}= frac{-x(2-x)}{2-x}= - x$