Question

Решите пожалуйста.Срочно!!!

Answer 1

1.
а) $\frac{2-b}{b}+ \frac{b-3}{3b^2}=\frac{3b*(2-b)+b-3}{3b^2}=\frac{6b-3b^2+b-3}{3b^2}=\frac{7b-3b^2-3}{3b^2}$
б) $\frac{3c+9}{6c}*\frac{2c^4}{c+3}=\frac{3(c+3)*2c^4}{6c*(c+3)}=c^3$
в) $\frac{x^2-y^2}{6y}:(x-y)^2=\frac{(x-y)*(x+y)}{6y*(x-y)^2}=\frac{x+y}{6y*(x-y)}$
2.
$\frac{5}{a}-\frac{a}{4-a}*\frac{16-a^2}{a^2}=\frac{5}{a}-\frac{a*(4-a)*(4+a)}{(4-a)*a^2}=\frac{5}{a}-\frac{4+a}{a}=\frac{5-4-a}{a}=\frac{1-a}{a}$
3.
$\frac{x^2+14xy+49y^2}{x^2-49y^2}*(21y-3x):(7x^2+49xy)= \\ \\ \frac{(x+7y)^2*(-3)*(x-7y)}{(x-7y)*(x+7y)*7x*(x+7y)}=-\frac{3}{7x} \\ \\ -\frac{3}{7*9}=-\frac{3}{63}=-\frac{1}{21}$