Question

用配方法解下列方程:(1)x^2-2x-5=0 (2)3x^2+2x-1=0

Answer 1

x^2-2x-5=0

x^2-2x=5

x^2-2x+1=6

(x-1)^2=6

x-1=±√6

x1=√6+1

x2=-√6+1

3x^2+2x-1=0

3x^2+2x=1

x^2+2/3x=1/3

x^2+2/3x+1/9=1/3+1/9

(x+1/3)^2=4/9

x+1/3=±2/3

x1=1/3,x2=-1