c) 4,9x > 0+7
49/10x > -7
x > -7 * 10/49
x > -10/7
x apartine (-10/7, infinit)
f) -V8x < 0-V2
-x < -V2/V8
x > 1/V4
x > 1/2
x apartine (1/2, infinit)
