а) \(\frac{1}{x} + \frac{1}{x+y} = \frac{1 \cdot (x+y) + 1 \cdot x}{x(x+y)} = \frac{x+y+x}{x(x+y)} = \frac{2x+y}{x(x+y)}\)
Ответ: \(\frac{2x+y}{x(x+y)}\)