Question

1、x²+2x-3=0 2、x²-7x+6=0 3、x²+2x-1=0

Answer 1

x²+2x-3=0

x²+2x+1-1-3=0

(x+1)²-4=0

(x+1+2)(x+1-2)=0

(x+3)(x-1)=0

x=3或x=-1

x²-7x+6=0

x²-7x+49/4-49/4+6=0

(x-7/2)^2-25/4=0

(x-7/2-5/2)(x-7/2+5/2)=0

(x-6)(x-1)=0

x=6或x=1

x²+2x-1=0

x²+2x+1-1-1=0

(x+1)^2-2=0

(x+1-√2)(x+1+√2)=0

x=-1+√2或x=-1-√2