Question

81-a²/a²＋6a＋9÷a-9/2a＋6×a+3/a+9.急需,要详细过程,谢谢.

Answer 1

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

=(9-a)(9+a)/(a+3)^2*2(a+3)/(a-9)*(a+3)/(a+9)

=-2