Giải thích các bước giải :
`a)x/(1-x)+(x^2+1)/(x^2-1)`
`=-x/(x-1)+(x^2+1)/[(x-1)(x+1)]`
`=[-x(x+1)]/[(x-1)(x+1)]+(x^2+1)/[(x-1)(x+1)]`
`=(-x^2-x+x^2+1)/[(x-1)(x+1)]`
`=-(x-1)/[(x-1)(x+1)]`
`=-1/(x+1)`
`b)P={(x+5)/(x^2-9)-1/(x+3)}.(x^2-3x)/(8x)`
`<=>P={(x+5)/[(x-3)(x+3)]-[1(x-3)]/[(x-3)(x+3)]}.[x(x-3)]/(8x)`
`<=>P={(x+5-x+3)/[(x-3)(x+3)]}.(x-3)/8`
`<=>P=8/[(x-3)(x+3)].(x-3)/8`
`<=>P=1/(x+3)`
`c)(x-2)/(4x-8).(2x+4)/(x-2)`
`=(2x+4)/(4x-8)`
`=[2(x+2)]/[4(x-2)]`
`=(x+2)/(2(x-2))`
~Chúc bạn học tốt !!!~
