化简后求值[(a+3)/(a^2-4)+a/(6-a-a^2)]除以(4a+9)/(5a-10),其中a=-8

问题描述:

化简后求值[(a+3)/(a^2-4)+a/(6-a-a^2)]除以(4a+9)/(5a-10),其中a=-8

[(a+3)/(a^2-4)+a/(6-a-a^2)]除以(4a+9)/(5a-10)先化简= [(a+3)/(a+2)(a-2)]-a/(a+3)(a-2)除以(4a+9)/(5a-10)通分 (a+2)(a-2)(a+3)=[(a+3)^2 - a(a+2)]/(a+2)(a-2)(a+3)除以(4a+9)/(5a-10)先化简,再约分 =(...