А) (x+8)(x-4)(x-7)>0
x= -8 x=4 x=7
- + - +
-------- -8 -------- 4----------- 7 -----------
\\\\\\\\\\ \\\\\\\\\\\
x= -9 - - - | -
x= 0 + - - | +
x= 5 + + - | -
x= 8 + + + | +
x∈(-8; 4)U(7; +∞)
b) (x-5)/(x+7)<0<br>ОДЗ: х≠ -7
(x-5)(x+7)<0<br>x=5 x= -7
+ - +
-------- -7 ----------- 5 ------------
\\\\\\\\\\\\\\
x= -8 - - | +
x=0 - + | -
x= 6 + + | +
x∈(-7; 5)