a) Rút gọn A
A = $\frac{2√x}{√x+3}$ + $\frac{√x+1}{√x-3}$ + $\frac{3-11√x}{9-x}$
= $\frac{2√x}{√x+3}$ + $\frac{√x+1}{√x-3}$ - $\frac{3-11√x}{(√x-3)(√x+3)}$
= $\frac{2x-6√x+x+4√x+3-3+11√x}{(√x-3)(√x+3)}$
= $\frac{3x+8√x}{(√x-3)(√x+3)}$
b) P = A×B
P = $\frac{3x+8√x}{(√x-3)(√x+3)}$ × $\frac{√x-3}{√x+1}$
= $\frac{3x+8√x}{√x+3}$ × $\frac{1}{√x+1}$
= $\frac{3x+8√x}{(√x+3)(√x+1)}$