Giải thích các bước giải:
$a)\dfrac{11x}{2x-3}+\dfrac{x+15}{3-2x}$
$=\dfrac{11x}{2x-3}-\dfrac{x-15}{2x-3}$
$=\dfrac{11x-x-15}{2x-3}$
$=\dfrac{5(2x-3)}{2x-3}$
$=5$
$b)\dfrac{2x}{x^2-1}+\dfrac{x-1}{2x+2}$
$=\dfrac{2x}{(x+1)(x-1)}+\dfrac{x-1}{2(x+1)}$
$=\dfrac{2x+x-1}{2(x+1)(x-1)}$
$=\dfrac{2x+2x-x-1}{2(x+1)(x+1)}$
$=\dfrac{x(2x-1)+(2x-1)}{2(x+1)(x+1)}$
$=\dfrac{(2x-1)(x+1)}{2(x+1)(x+1)}$
$=\dfrac{2x-1}{2x+2}$
$c)\dfrac{x^3-8}{4x-12}.\dfrac{x^2-3x}{x^2+2x+4}$
$=\dfrac{(x-2)(x^2+2x+4)}{4(x-3)}.\dfrac{x(x-3)}{x^2+2x+4}$
$=\dfrac{x^2-2x}{4}$
