1) (x-4)(x+8)<0<br>x=4 x=-8
+ - +
-------- -8 --------- 4 ------------
\\\\\\\\\\\\
x∈(-8; 4)
2) (3-x)(x+1)(x-4)≥0
-(x-3)(x+1)(x-4)≥0
(x-3)(x+1)(x-4)≤0
x=3 x=-1 x=4
- + - +
-------- -1 --------- 3 ------------ 4 -----------
\\\\\\\\\ \\\\\\\\\\\\\
x∈(-∞; -1]U[3; 4]
3) x²-4x-77<0<br>Разложим на множители:
x²-4x-77=0
D=16+308=324
x₁=4-18=-7
2
x₂=4+18=11
2
(x+7)(x-11)<0<br>x=-7 x=11
+ - +
--------- -7 ------------ 11 -----------
\\\\\\\\\\\\\\\
x∈(-7; 11)