计算:(3a+6)/(a²-6a+9)÷(a+2)*(9-a²)/((a+2)(a+3))

问题描述:

计算:(3a+6)/(a&sup2-6a+9)÷(a+2)*(9-a&sup2)/((a+2)(a+3))

(3a+6)/(a²-6a+9)÷(a+2)*(9-a²)/((a+2)(a+3))
=3(a+2)/[(a-3)²(a+2)]× (3+a)(3-a)/[(a+2)(a+3)]
=-3/[(a+2)(a+3)]

(3a+6)/(a²-6a+9)÷(a+2)*(9-a²)/((a+2)(a+3))=3(a+2)/(a-3)²÷(a+2)*[-(a+3)(a-3)/(a+2)(a+3)]=3/(a-3)²*[-(a-3)/(a+2)]=-3/(a+2)(a-3)=-3/(a²-a-6)