1)13 + x³ -9x² ≤ x³ -9x² +27x -27 + 11
-27x ≤ -29
x ≥ 29/27
2) 26 +8 +12x + 6x² +x³ < 6x² + x³
12x < -34
x < -34/12
x < -17/6
3) 3x -15x² -x³ > -x³ -15x² -75 x - 125 - 4x
82x > -125
x > -125/82
4) 64 + 48x + 12x² + x³ -6x ≤ x³ + 12x² +1
42x ≤ -63
x ≤ -63/42
x ≤ -1,5