Đáp án + Giải thích các bước giải:
`P = (4/(x + 3) + 3/(x-3)-(5x+3)/(x^2-9))*(2x+6)/4(xnepm3)` $\\$ `= (4/(x+3) + 3/(x-3)-(5x+3)/[(x-3)(x+3)])*(2x+6)/4` $\\$ `= ([4(x - 3)]/[(x-3)(x+3)]+[3(x+3)]/[(x-3)(x+3)] - (5x + 3)/[(x - 3)(x+3)])*(2x+6)/4` $\\$ `= (4(x - 3) + 3(x + 3) - 5x - 3)/[(x-3)(x+3)]* [2(x+3)]/4` $\\$ `= (4x - 12 + 3x + 9 - 5x - 3)/[(x-3)(x+3)] * [2(x+3)]/4` $\\$ `= (2x - 6)/[(x - 3)(x + 3)] * [2(x + 3)]/4` $\\$ `= [2(x - 3)]/[(x - 3)(x + 3)] * [2(x + 3)]/4` $\\$ `= [4(x-3)(x+3)]/[4(x-3)(x+3)] = 1`
Vậy `P = 1` khi `x ne pm 3`
