Question

Пожалуйста помогите, очень надо. №6

Answer 1

x²+x=a⇒x(x+1)=a⇒x²(x+1)²=a²
1/x²+1/(x+1)²-2/x(x+1)-1/a²=
=[(x+1)²+x²-2x(x+1)]/x²(x+1)²-1/a²=
(x²+2x+1+x²-x²-2x)/x²(x+1)²-1/a²=
1/x²(x+1)²-1/a²=1/a²-1/a²=0

Answer 2

a=x*(x+1)
1/(x^2)+1/((x+1)^2)-1/(x^2*(x+1)^2)-2/(x*(x+1))=
=((x+1)^2+x^2-1-2*x*(x+1))/(x^2*(x+1^2))=
=(x^2+2*x+1+x^2-1-2*x^2-2*x)/(x^2*(x+1)^2)=
=0/(x^2*(x+1)^2)=0