Question

помогите!!!!!!!!!!!!!!!

Answer 1

1) $frac{y+2xy}{x^2-y}|_{x=0,y=-1}= frac{-1+2*0*(-1)}{0^2-(-1)}=frac{-1}{1}=-1$

2) $frac{a}{a+2b},and,frac{-2b}{2b-a}$

$frac{a}{a+2b}* frac{a-2b}{a-2b},and,frac{2b}{-(2b-a)}*frac{a+2b}{a+2b}$

$frac{a(a-2b)}{(a+2b)(a-2b)},and,frac{2b(a+2b)}{-(2b-a)(a+2b)}$

$frac{a(a-2b)}{(a+2b)(a-2b)},and,frac{2b(a+2b)}{(a-2b)(a+2b)}$

3) $2frac{1}{4}a^{-1}b^3*(frac{2}{9}a^2b^{-3})= frac{2*4+1}{4}* frac{2}{9}*a^{-1}*a^2*b^3*b^{-3}=$

$=frac{9}{4}* frac{2}{9}*a^{-1+2}*b^{3+(-3)}=frac{2}{4}*a^1*b^0=0.5a=frac{a}{2}$

4) $frac{2x}{3}:frac{3}{2x}*frac{9}{4xy}:frac{x}{2y}=(frac{2x}{3}:frac{3}{2x})*frac{9}{4xy}:frac{x}{2y}=(frac{2x}{3}*frac{2x}{3})*frac{9}{4xy}:frac{x}{2y}=$

$=frac{2x*2x*9}{3*3*4xy}:frac{x}{2y}=frac{4x^2*9}{9*4xy}*frac{2y}{x}=frac{4x^2}{4xy}*frac{2y}{x}=frac{4x^2y*2}{4x^2y}=2$

5) $frac{1-x}{2}+frac{2+3x}{5}+frac{x}{6}=frac{1}{30}$

$frac{(1-x)*15}{2*15}+frac{(2+3x)*6}{5*6}+frac{x*5}{6*5}=frac{1}{30}$

$15(1-x)+6(2+3x)+5x=1$

$15-15x+12+18x+5x=1$

$8x=-26$

$2*4x=2*13$

$4x=13$

$x=frac{13}{4}$