Question

Выполните:


1) 3/(x+3) + (x+4)/(x^2-9)

Answer 1

Ответ:

3/(x+3) + (x+4)/(x^2-9)=(3(3x-3)+x+4)/((x2-9))=(3x-9+x+4)/(x2-9)=(4x-5)/(x2-9)

Answer 2

$\frac{3}{x + 3} + \frac{x + 4}{ {x}^{2} - 9 } = \frac{3}{x + 3} + \frac{x + 4}{(x - 3)(x + 3)} = \frac{3(x - 3) + x + 4}{(x - 3)(x + 3} = \frac{3x - 9 + x + 4}{(x - 3)(x + 3)} = \frac{4x - 5}{(x - 3)(x + 3)} = \frac{4x - 5}{ {x}^{2} - 9 }$