giúp mik với ạ :(((((((((((((((((

Đáp án:

Giải thích các bước giải:

$a,\frac{9-x^{2}}{5x+5}:\frac{2x-6}{3x+3}$

$=\frac{(3-x)(x+3)}{5.(x+1)}.\frac{3.(x+1)}{2.(x-3)}$

$=\frac{3.(x+3)}{10}$

$=\frac{3x+9}{10}$

$b,(x+2)^{2}-(x-2)(x+2)+5x$

$=(x+2).[x+2-(x-2)]+5x$

$=(x+2).(x+2-x+2)+5x$

$=(x+2).4+5x$

$=4x+8+5x$

$=9x+8$

$c,\frac{3}{2x+6}-\frac{x-6}{2x^{2}+6x}$

$=\frac{3}{2.(x+3)}-\frac{x-6}{2x.(x+3)}$

$=\frac{3x}{2x.(x+3)}-\frac{x-6}{2x.(x+3)}$

$=\frac{3x-(x-6)}{2x.(x+3)}$

$=\frac{3x-x+6}{2x.(x+3)}$

$=\frac{2x+6}{2x.(x+3)}$

$=\frac{2.(x+3)}{2x.(x+3)}$

$=\frac{1}{x}$

(Bài tham khảo)