Question

(1)2x^2-x-1=0 (2)1/4x^2-6x+3=0 (3)3x^2-4x-1=0 (全部用配方法)

Answer 1

⑴X^2-1/2X=1/2

(X-1/4)^2=9/16,

X-1/4=±3/4,

X=1/4±3/4,

X1=1,X2=-1/2.

⑵X^2-24X=-12

(X-12)^2=132

X-12=±2√33,

X1=12+√33,X2=12-√33.

⑶X^2-4/3X=1/3,

(X-2/3)^2=7/9

X-2/3=±√7/3

X1=(2+√7)/3,X2=(2-√7)/3.