用配方法解下列方程: (1)3x눀-2x-7=0 (2)x눀-6x-11=0

2024-12-12 02:15:32
推荐回答(2个)
回答1:

解:(1)3x²-2x-7=0
x²-(2/3)x-(7/3)=0
x²-(2/3)x=7/3
x²-(2/3)x+(1/3)²=(7/3)+(1/3)²
[x-(1/3)]²=22/9
x-(1/3)=±(1/3)√22
∴x1=(1/3)(1+√22), x2=(1/3)(1-√22)

(2) x²-6x-11=0
x²-6x=11
x²-6x+9=11+9
(x-3)²=20
x-3=±2√5
∴x1=3+2√5, x2=3-2√5.

回答2:

解:(1)3x²-2x-7=0
x²-(2/3)x-(7/3)=0
x²-(2/3)x=7/3
x²-(2/3)x+(1/3)²=(7/3)+(1/3)²
[x-(1/3)]²=22/9
x-(1/3)=±(1/3)√22
∴x1=(1/3)(1+√22), x2=(1/3)(1-√22)

(2) x²-6x-11=0
x²-6x=11
x²-6x+9=11+9
(x-3)²=20
x-3=±2√5
∴x1=3+2√5, x2=3-2√5.
这个配方只需要将系数配好就行了