√(2-х)(х+4) = √(2х-х²+8-4х) =
√(-х²-2х+8).
-х²-2х+8 ≥ 0;
d = 36.
х1 = -4;
х2 = 2.
---(-)--(-4)--(+)----(2)-(-)---→x
ответ: [-4;2].
2/(x-12) < 0
- +
_______________12 ________________
x∈(-∞;12)
1) (x+y-2c)(x+y+2c)=(x+y)²-(2c)²=(x+y)²-4c².
2)(a+1)(a+2)(a-1)(a+2)=(a+2)²*(a²-1).
3) (a+b)+x*(a+b)²+y*(a+b)³=(a+b)(1+x*(a+b)+y*(a+b)²).