А) 2x²+3x-9>0
2x²+3x-9=0
D=3²+4*2*9=9+72=81
x₁=-3-9= -3
4
x₂= -3+9 =1.5
4
+ - +
-------- -3 ------------- 1.5 -------------
\\\\\\\\\ \\\\\\\\\\\\\\
x∈(-∞; -3)U(1.5; +∞)
б) 5x-x²<0<br>x²-5x>0
x(x-5)>0
x=0 x=5
+ - +
-------- 0 ------------ 5 ---------------
\\\\\\\\ \\\\\\\\\\\\\\\\\
x∈(-∞; 0)U(5; +∞)