$\frac{2}{x+1}$ - $\frac{2}{x+2}$ = 1
ĐKXĐ: x $\neq$ -1 ; x $\neq$ -2
<=>$\frac{2(x+2)}{(x+1)(x+2)}$ - $\frac{2(x+1)}{(x+1)(x+2)}$ = 1
<=>$\frac{2(x+2)-2(x+1)}{(x+1)(x+2)}$ = 1
<=>2(x+2) - 2(x+1) = (x+1)(x+2)
<=>2x + 4 - 2x - 2 = x² + 3x + 2
<=>x² + 3x =0
<=>x(x+3)=0
TH1: x = 0 (TM)
TH2: x+3=0 <=> x = -3 (TM)