1)2x²+3x-9>0
D=9+72=81
x1=(-3-9)/4=-3
x2=(-3+9)/4=1,5
+ _ +
___________________
-3 1,5
x∈(-∞;-3) U (1,5;∞)
2)8x-x²<0<br>x²-8x>0
x(x-8)>0
x=0 x=8
+ _ +
_________________________
0 8
x∈(-∞;0) U (8;∞)
3)(x+3)(1-x)>0
x=-3 x=1
_ + _
__________________________
-3 1
x∈(-3;1)
4)(x-3)/(x-1)<0<br>x=3 x=1
+ _ +
_____________________________________
1 3
x∈(1;3)