x^2+2x分之x^2 -x+2分之x^2-2x+1÷x+1分之x^2-1
=x²+(x²-x)/2x+(x²-2x+1)/2÷(x²-1)/(x+1)
=x²+(x-1)/2+(x-1)²/2÷(x-1)
=x²+(x-1)/2+(x-1)/2
=x²+x-1
=x²+x+(1/2)²-(1/2)²-1
=(x+1/2)²-5/4

(x+1/2)²-5/4=0
x=±√5/2-1/2=(±√5-1)/2=(√5-1)/2,(-√5-1)/2(不合題意,舍去)
∴x=(√5-1)/2什么意思啊，能明確一點(diǎn)么x^2+2x分之x^2 -x+2分之x^2-2x+1÷x+1分之x^2-1=x²+(x²-x)/2x+(x²-2x+1)/2÷(x²-1)/(x+1)=x²+(x-1)/2+(x-1)²/2÷(x-1)=x²+(x-1)/2+(x-1)/2=x²+x-1=x²+x+(1/2)²-(1/2)²-1=(x+1/2)²-5/4當(dāng)x=0時(shí)，原式=-1當(dāng)x=5時(shí)，原式=29 ∵0＜x＜5所以-1＜原式＜29上面那些答案怎么會(huì)有4分之5出來的？ 要分式化簡啊，后面明明是5的平方根- -5的平方根的整數(shù)：2∴x＜5的平方根的整數(shù)，即 x＜2. 當(dāng)x=2時(shí)，原式=5. ∵0＜x＜5所以-1＜原式＜5.