Đáp án `+` Giải thích các bước giải `!`
`B= ((x^2)/(x^2+3x)+1/(x+3)) : (1-2/x+6/(x^2+3x))` `(x \ne 0; x \ne -3)`
`= [(x^2)/(x(x+3))+1/(x+3)] : [1-(2)/(x)+6/(x(x+3))]`
`= (x+1)/(x+3) : [(x(x+3))/(x(x+3))-(2(x+3))/(x(x+3))+6/(x(x+3))]`
`= (x+1)/(x+3) : [(x^2+3x-2x-6+6)/(x(x+3))]`
`= (x+1)/(x+3) : [(x^2+x)/(x(x+3))]`
`= (x+1)/(x+3) : (x(x+1))/(x(x+3))`
`= (x+1)/(x+3). (x+3)/(x+1)`
`= 1`
