3 ( х - 4 ) - 7х = 8
3х - 3 * 4 - 7х = 8
3х - 12 - 7х = 8
- 4х - 12 = 8
- 4х = 8 + 12
- 4х = 20
х = 20 : ( - 4 )
х = - 5
1) f(x)=(2x+x^2+1)^3
5х/4 * 8/х = 40х/4х = 10.............