[1/a(a+2b) - 1/a(a-2b)]:[4b²/(4b²-a²) = [(a-2b)-(a+2b)]/[a(a²-4b²)]*[(4b²-a²)/4b²]= (-4b/a)*(-1/4b²) = 1/ab 1/ab = 1/(-1)*(1) = -1 Ответ: - 1