Question

(a^2-6a+9)/(4-b^2)÷(3-a)/(2+b)*(a^2)/3a-9

Answer 1

原式=（a²-6a+9)/(4-b²)*(2+b)/(3-a)*a²/3a-9

=(a-3)²/(2+b)(2-b)*(2+b)/(3-a)*a²/3(a-3)

约分后得：-a²/3(2-b)