解方程：-3x²-2x+4=0 x²+2x-99=0 x²-6mx+5

网友回答

-3x²-2x+4=0
3x²+2x-4=0
3(x²+2/3x)=4
3(x²+2/3x+1/9)=4+1/3
3(x+1/3)²=13/3
(x+1/3)²=13/9
x+1/3=±√13/3
解得x=(√13-1)/3或x=-(√13+1)/3
x²+2x-99=0
x²+2x+1=100
(x+1)²=100
x+1=±10
解得x=9或x=-11
x²-6mx+5m²=0
(x-5m)(x-m)=0
解得x=5m或x=m
======以下答案可供参考======
供参考答案1:
3x²-2x+4=0
3x²+2x-4=0
3(x²+2/3x)=4
3(x²+2/3x+1/9)=4+1/3
3(x+1/3)²=13/3
(x+1/3)²=13/9
x+1/3=±√13/3
解得x=(√13-1)/3或x=-(√13+1)/3
x²+2x-99=0
x²+2x+1=100
(x+1)²=100
x+1=±10
解得x=9或x=-11
x²-6mx+5m²=0
(x-5m)(x-m)=0
解得x=5m或x=m