在實(shí)數(shù)范圍內(nèi)分解因式:x2+2x-1= .
【答案】
分析:此題可以運(yùn)用配方法或公式法進(jìn)行因式分解.
解答:解:原式=x
2+2x+1-2=(x+1)
2-2=(x+1+
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103200109147106540/SYS201311032001091471065002_DA/0.png)
)(x+1-
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103200109147106540/SYS201311032001091471065002_DA/1.png)
).
故答案為(x+1+
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103200109147106540/SYS201311032001091471065002_DA/2.png)
)(x+1-
![](http://thumb.zyjl.cn/pic6/res/czsx/web/STSource/20131103200109147106540/SYS201311032001091471065002_DA/3.png)
).
點(diǎn)評(píng):此題考查了實(shí)數(shù)范圍內(nèi)的因式分解,亦可運(yùn)用公式法.
即若ax
2+bx+c=0的兩個(gè)根是x
1、x
2,則ax
2+bx+c=a(x-x
1)(x-x
2)