在线等初二数学题-化简下列分式:1.（x^2+x）/(x^2-1) 2.(x^2-9)/(x^2-6

Question

在线等初二数学题-化简下列分式:1.（x^2+x）/(x^2-1)
2.(x^2-9)/(x^2-6x+9)
3.先化简后求值 x=5.(x^2-8x+16)/(x^2-16)
都是分数来的

Answer 1

1.（x^2+x）/(x^2-1)=x(x+1)/(x-1)(x+1)=x/(x-1)

2.(x^2-9)/(x^2-6x+9)

=(x-3)(x+3)/(x-3)²
=(x+3)/(x-3)
3.(x^2-8x+16)/(x^2-16)
=(x-4)²/(x+4)(x-4)
=(x-4)/(x+4)
=(5-4)/(5+1)
=1/9

Answer 2

1.原式=[x(x+1)]/[(x+1)(x-1)]=x/(x-1)
2.原式=[(x+3)(x-3)]/(x-3)²=(x+3)/(x-3)
3.原式=(x-4)²/[(x+4)(x-4)]=(x-4)/(x+4)=(5-4)/(5+4)=1/9

Answer 3

答案如图所示，因式分解就好了