A = $\frac{x}{x - 4}$ + $\frac{1}{√x - 2}$ + $\frac{1}{√x + 2}$ (đkxđ : x$\neq$ 4)
= $\frac{x}{(√x - 2)(√x + 2)}$ + $\frac{√x + 2}{(√x - 2)(√x + 2)}$ + $\frac{√x - 2}{(√x - 2)(√x + 2)}$
= $\frac{x + √x + 2 + √x - 2}{x-4}$
= $\frac{x + 2√x}{x - 4}$
= $\frac{√x ( √x + 2 )}{(√x - 2)(√x + 2)}$
= $\frac{√x}{√x - 2}$
~CHÚC BẠN HỌC TỐT~