Bună,
a) (x-3)²-17 ≤ (x+1)²+7
x²-6x+9-17 ≤ x²+2x+1+7
x²-6x-8 ≤ x²+2x+8
x²-6x-x²-2x ≤8+8
-8x ≤ 16 /•(-1)
8x ≥ -16
x ≥ -2.
x € [-2;+∞).
b) (2x-1)²-2x ≥ (2x-3)²+4
4x²-4x+1-2x ≥ 4x²-12x+9+4
4x²-6x+12x-4x² ≥ 13-1
6x ≥ 12
x ≥ 2.
x € [2;+∞).
c) (x-2)²+3x ≥ (x+1)²+9
x²-4x+4+3x ≥ x²+2x+1+9
x²-x+4 ≥ x²+2x+10
x²-x-x²+2x ≥ 10-4
x ≥ 6.
x € [6;+∞).
Succes!
