(1)分解因式:x²-5x+4=(x-1)(x-4)(2)已知a²-2a+b²+2b+2=0,求a-b的值.a²-2a+b²+2b+2=0得(a-1)²+(b+1)²=0所以a-1=0,b+1=0解得a=1,b=-1a-b=1-(-1）=2(3)试说明:不管a,b取任何值,2a...
阅读下面一道例题的解答过程:分解因式3x² +7+4
(1)分解因式:x²-5x+4=(x-1)(x-4)(2)已知a²-2a+b²+2b+2=0,求a-b的值.a²-2a+b²+2b+2=0得(a-1)²+(b+1)²=0所以a-1=0,b+1=0解得a=1,b=-1a-b=1-(-1）=2(3)试说明:不管a,b取任何值,2a...