Question

Прошу сократить
 1)  $frac{3x-y}{x-2y}$ * $frac{2x+4y}{9x^2+6xy+y^2}$ 
2) $frac{x^2-y^2}{27x^3}$ * $frac{18x^2}{xy-y^2}$
3) $frac{a-20}{a-8}$ / $frac{a^2-400}{a^2-16a+64}$
4) $frac{xy}{xy+3y^2}$ / $frac{x^2}{x^2+6xy+9y^2}$

Answer 1

$1)...=frac{3x-y}{x-2y}cdot frac{2(x+2y)}{(3x+y)^2}\2)...=frac{(x-y)(x+y)cdot 18x^2}{27x^3cdot y(x-y)}=frac{2(x+y)}{3xy}\3) ...=frac{(a-20)(a-8)^2}{(a-8)(a-20)(a+20)}=frac{a-8}{a+20}\4)...=frac{xycdot (x+3y)^2}{y(x+3y)cdot x^2}=frac{x+3y}{x}$