Câu `14`

`P=((2x-1)/(x+3)-x/(3-x)-(3-10x)/(x^2-9)): (x+2)/(x-3) (đk: x ne 3;x ne -3;x ne -2)`

`P=[(2x-1)/(x+3)+x/(x-3)-(3-10x)/((x-3)(x+3))] . (x-3)/(x+2)`

`P=((2x-1)(x-3)+x(x+3)-3+10x)/((x-3)(x+3)) . (x-3)/(x+2)`

`P=(2x^2-6x-x+3+x^2+3x-3+10x)/((x-3)(x+3)) . (x-3)/(x+2)`

`P=(3x^2+6x)/((x-3)(x+3)) . (x-3)/(x+2))`

`P=(3x(x+2))/((x-3)(x+3)) . (x-3)/(x+2))`

`P=(3x)/(x+3)`

Câu `15`

`M=(x/(x^2-9)+1/(x+3)+2/(3-x)): 3/(x+3) (đk: x ne 3;x ne -3)`

`M=[x/((x-3)(x+3))+1/(x+3)-2/(x-3)] . (x+3)/3`

`M=(x+x-3-2(x+3))/((x-3)(x+3)) . (x+3)/3`

`M=(2x-3-2x-6)/((x-3)(x+3)) . (x+3)/3`

`M=(-9)/((x-3)(x+3)) . (x+3)/3`

`M=-3/(x-3)`