解以下一元二次不等式:1.x²+4x-12≥02.x²+8x+16≥03.2x²-2x-7≥04.-2x²-4x+6≤0
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解以下一元二次不等式:1.x²+4x-12≥02.x²+8x+16≥03.2x²-2x-7≥04.-2x²-4x+6≤0
解以下一元二次不等式:
1.x²+4x-12≥0
2.x²+8x+16≥0
3.2x²-2x-7≥0
4.-2x²-4x+6≤0
解以下一元二次不等式:1.x²+4x-12≥02.x²+8x+16≥03.2x²-2x-7≥04.-2x²-4x+6≤0
1.
x²+4x-12≥0
(x-2)*(x+6)≥0
∴ x=2
2.
x²+8x+16≥0
(x+4)^2≥0
∴ x∈R
3
2x²-2x-7≥0
由2x²-2x-7=0 得x=(1+√15)/2 或 =(1-√15)/2
∴ x=(1-√15)/2
4.
-2x²-4x+6≤0
x²+2x-3≥0
(x-1)*(x+3)≥0
∴ x=1