Question

求具体.用配方法解下列方程：x²+2x+1=4,x²-x-3/4=0,4x²-x-9=0

Answer 1

x²+2x+1=4

(x+1)²=4

x+1=2或x+1=-2

解得x=1或x=-3

x²-x-3/4=0

x²-x+1/4=1

(x-1/2)²=1

x-1/2=1或x-1/2=-1

解得x=3/2或x=-1/2

4x²-x-9=0

4x²-x+1/16=9+1/16

(2x-1/4)²=145/16

2x-1/4=√145 /4或2x-1/4=-√145 /4

解得x=(√145+1)/8或x=(1-√145)/8

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