X²-4ax+4=0
D<0
D=(-4a)²-4*1*4=16a²-16
16a²-16<0 |:16
a²-1<0
(a-1)(a+1)<0
+ - +
__________-1__________1__________
a∈(-1;1)
.......................................................
1) f(0.5a + 2) = -6(0.5a+2)^2 = -1.5a^2 - 6a -24
2) 2f(x^2 - 1) = -12(x^2 - 1)^2 = -12x^4 +24x^2 - 12