2x-4/x^2/x^2+3x除以x-2/x^2+6x+9 (a-5)乘以25-a^2/a^2-10a+25 a^2-4a+4/9a^2+6a+1除以6-3a/3a+1 请计算

(1)2x-4/x^2/x^2+3x除以x-2/x^2+6x+9=[2(x-2)(x+3)²]/[x(x+3)(x-2)]=2(x+3)/x=2+6/x(2)(a-5)乘以25-a^2/a^2-10a+25 =[-(a-5)(a-5)(a+5)]/[(a-5)²]=-(a+5)(3)a^2-4a+4/9a^2+6a+1除以6-3a/3a+1 =[(a-2)²...