lài 15 Cho A=(x)/(x-2)+(2-x)/(x+2)+(12-10x)/(x^2)-4 a) Rút gọn A

a) <br />* Ta có: $x^2 - 4 = (x-2)(x+2)$<br />* Rút gọn A:<br />$A = \frac {x}{x-2}+\frac {2-x}{x+2}+\frac {12-10x}{x^{2}-4}$<br />$A = \frac {x(x+2)}{(x-2)(x+2)} + \frac {(2-x)(x-2)}{(x+2)(x-2)} + \frac {12-10x}{(x-2)(x+2)}$<br />$A = \frac {x^2 + 2x + 2x - x^2 - 4 + 12 - 10x}{(x-2)(x+2)}$<br />$A = \frac {-6x + 8}{(x-2)(x+2)}$<br />$A = \frac {-2(3x - 4)}{(x-2)(x+2)}$<br /><br />Vậy $A = \frac {-2(3x - 4)}{(x-2)(x+2)}$