Ответ:
(х+1)^2+(х-6)^2=2x^2
x^2+2x+1+x^2-12x+36=2x^2
2x^2-10x+37=2x^2
-10x+37=0
-10x=-37
x=37
10x=37:10
x=3,7
1) = -5х* (-9/5)=-х*(-9)=9х
2)=18/27*12/9=24/27
3) =3b^2
4)=0.75x^3y^3