初一数学因式分解题
\u521d\u4e00\u6570\u5b66\u9898\uff1a\u56e0\u5f0f\u5206\u89e3\u89e3\uff1a\uff081\uff09x²+1=2x
\uff08x-1\uff09²=0
x=1
\uff082\uff09(x+2\uff09\uff08x+4\uff09=x²+6x+8
\u5219a=6
\uff08x+1\uff09\uff08x+9\uff09=x²+10x+9
\u5219b=9
x²+6x+9=\uff08x+3\uff09²
\uff083\uff09x²+x+1/4=0
\uff08x+1/2\uff09²=0
x=-1/2
\uff084\uff09\uff08x²-14x+49\uff09/\uff08x²-49\uff09=\uff08x-7\uff09²/\uff08x+7\uff09\uff08x-7\uff09
=\uff08x-7\uff09/\uff08x+7\uff09
\uff085\uff09x(x+y)(x-y)-x(x+y)²=x(x+y)(x-y-x-y)
=-2xy(x+y)
=-2*\uff08-1/2\uff09=1
ab\uff08a+b\uff09² -\uff08a+b\uff09-1
\u9898\u6709\u95ee\u9898
a²+ab-2b²
=(a+2b)(a-b)
x²-4xy+4y²-3x+3y+2
\u9898\u6709\u95ee\u9898
=m(m-n)²-n（m-n)²
= (m-n)(m-n)²
=(m-n)³
2.解：原式=（3m+2n)²-（m-n)²
=(3m+2n+m-n)(3m+2n-m+n)
=(4m-n)(2m+3n)
3.解：原式=x³-15x²y-16xy²
=x(x²-15xy-16y²）
=x(x-16y)(x+y)
4.解：原式=-y³-y²-4分之1y
=y(y²-y-1/4）
=y(y-1/2）²
5.解：原式=3分之1x-3x³
=1/3x（1-9x²）
=1/3x(1+3x)(1-3x)
同学：呵呵你是否发现2a^2+a可以先视为一个X
则有2*X^2-11X-6=(X-6)(2X+1)
{用
十字交叉法
}
在把X=2a^2+a代入有（2a^2+a-6）*
（4a^2+2a+1）=（a+2）*（2a-3）*（4a^2+2a+1）{用十字交叉法}
解：
令（2a的平方+a）=A
所以原式=2A的平方-11A-6
根据因式分解
所以原式=（A-6）（2A+1）
又A=2a的平方+a
所以原式=（A-6）（2A+1）=（2a的平方+a-6）（2a的平方+a+1）
再根据因式分解
所以原式=（a-2）(2a+3)(2a的平方+a+1)
x²+4x+4-y²+6y-9=x²-y²
4x+6y=5
(1)
x-3y=2
(1)
(1)+(2)*2
4x+6y+2x-6y=5+4
6x=9
x=3/2
y=(x-2)/3=-1/6
4(x+2y)²-25(x-y)²
=[2(x+2y)]²-[5(x-y)]²
=[2(x+2y)+5(x-y)][2(x+2y)-5(x-y)]
=(7x-y)(-3x+9y)
原式=(1-1/2)(1+1/2)(1-1/3)(1+1/3)……(1-1/2005)(1+1/2005)
=(1/2)(3/2)(2/3)(4/3)……(2004/2005)(2006/2005)
=(1/2)(2006/2005)
=1003/2005
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