Đáp án:
`a) (x^3-8)/(2x^2+4x+8)`
`=((x-2)(x^2+2x+4))/(2(x^2+2x+4))`
`=(x-2)/2`
`b)4/(x+2)+3/(x-2)+(5x+2)/(4-x^2)`
`=4/(x+2)+3/(x-2)-(5x+2)/(x^2-4)`
`=4/(x+2)+3/(x-2)-(5x+2)/((x-2)(x+2))`
`MTC: (x-2)(x+2)`
`=(4(x-2))/((x-2)(x+2))+(3(x+2))/((x-2)(x+2))-(5x+2)/((x-2)(x+2))`
`=(4(x-2)+3(x+2)-(5x+2))/((x-2)(x+2))`
`=(4x-8+3x+6-5x-2)/((x-2)(x+2))`
`=(2x-4)/((x-2)(x+2))`
`=(2(x-2))/((x-2)(x+2))=2/(x+2)`