Question

Даю 75 баллов.Решите пожалуйста,срочно

Answer 1

1.
a) (y²+y)/y²=y*(y+1)/y²=(y+1)/y.
b) (a²-2a)/(a²-4)=a*(a-2)/((a-2)*(a+2))=a/(a+2).
2.
a) 3/a+(a-3)/(a+5)=(3*(a+5)+a*(a-3))(a*(a+5))=(3a+15+a²-3a)/(a*(a+5))=
=(a²+15)/(a*(a+5))=(a²+15)/(a²+5a).
b) 2x²/(x²-4)-2x/(x+2)=2x²/((x-2)*(x+2))-2x/(x+2)=(2x²-2x*(x-2))/((x+2)*(x-2))=
=(2x²-2x²+4x)/((x-2)*(x+2))=4x/(x²-4).
3.
(y²-6y+9)/(y²-9):(10y-30)/(y²+3y)=(y-3)²/((y-3)*(y+3)):(10*(y-3)/(y*(y+3))=
=(y-3)/(y+3):(10*(y-3)/(y*(y+3))=(y-3)*y*(y+3)/((y+3)*10*(y-3))=y/10=70/10=7.
4.
x/y=a      y/z=1/a      x/z-?
y=z/a  ⇒
x/(z/a)=a
a*x/z=a  |÷a
x/z=1.
Ответ: x/z=1.