7
3x^2 - 12x <=0</p>
3x(x - 4) <=0</p>
++++++++++[0] --------------- [4] ++++++++++
x∈[0 4]
8
5x - 7x^2 > 0
x(5 - 7x) > 0
------------ (0) ++++++++ (7/5) ----------
x∈(0 7/5)
9
3x^2 < 10x
3x^2 - 10x < 0
x(3x - 10) < 0
++++++++++ (0) ------------- (10/3) +++++++
x∈(0 10/3)