1.若x1、x2是一元二次方程x²-3x+2=0的两根,则x1+x2的值是( ) A.-2 B.2 C.3 D.1
问题描述:
1.若x1、x2是一元二次方程x²-3x+2=0的两根,则x1+x2的值是( ) A.-2 B.2 C.3 D.1
解方程:(1)x²-4x-3=0 (2)(x-3)²+2x(x-3)=0 (3)4(x-1)²=36
答
选C解方程:(1)x²-4x-3=0 x²-4x+4=7(X-2)²=7X-2=±√7X1=2+√7 X2=2-√7 (2)(x-3)²+2x(x-3)=0 (x-3)(x-3+2x)=0(x-3)(3x-3)=0x1=3 x2=1 (...