~PVZ2~

`M=[2x-10]/[x^2-7x+10]-[2x]/[x^2-4]+1/[2-x] (x ne +-2; x ne 5)`

`M=[2x-10]/[(x-2)(x-5)]-[2x]/[(x-2)(x+2)]-1/[x-2]`

`M=[2(x-5)]/[(x-2)(x-5)]-[2x]/[(x-2)(x+2)]-1/[x-2]`

`M=2/[x-2]-[2x]/[(x-2)(x+2)]-1/[x-2]`

`M=[2(x+2)]/[(x-2)(x+2)]-[2x]/[(x-2)(x+2)]-[x+2]/[(x-2)(x+2)]`

`M=[2x+4-2x-x-2]/[(x-2)(x+2)]`

`M=[-x+2]/[(x-2)(x+2)]`

`M=[-(x-2)]/[(x-2)(x+2)]`

`M=[-1]/[x+2]`

`b) M` nguyên khi

`[-1]/[x+2] in ZZ`

`<=> -1 vdots x+2`

`<=> x+2 in Ư(-1)=Ư(1)`

`<=> x in {-1;-3}` (nhận)