①x2+2x-99=0, (x+11)(x-9)=0, x+11=0,x-9=0, x1=-11,x2=9.
②(2x-1)2=x(6x-3), (2x-1)2-3x(2x-1)=0, (2x-1)(2x-1-3x)=0, 2x-1=0,2x-1-3x=0, x1=,x2=-1.
③4x2-8x+1=0, b2-4ac=(-8)2-4×4×1=48, x=, x1=,x2=.
④(2x-3)2-121=0, (2x-3+11)(2x-3-11)=0, 2x-3+11=0,2x-3-11=0, x1=-4,x2=7.
⑤x2-2x+3=0, (x-)2=0, x-=0, x1=x2=.
⑥2(x-3)2=9-x2, 2(x-3)2-(x+3)(x-3)=0, (x-3)(2x-6-x-3)=0, x-3=0,x-9=0,
⑦-3x2-4x+4=0, 3x2+4x-4=0, (3x-2)(x+2)=0, 3x-2=0,x+2=0, x1=,x2=-2.
⑧(x+1)(x-1)+2(x+3)=8, 整理得:x2-2x-3=0, (x-3)(x+1)=0, x-3=0,x+1=0, x1=3,x2=-1.
⑨(x+1)2=4(x-2)2. x+1=±2(x-2) x1=-5,x2=1. |