a2+b2+4a-6b+13=0a^2+4a+4+b^2-6b+9=0(a+2)^2+(b-3)^2=0则a=-2,b=3(a^3-4ab^2)÷(b/a+1/b)÷（a2-2ab）=a(a^2-4b^2)÷[(b^2+a)/ab]÷a（a-2b）=a(a+2b)(a-2b)*[ab/(b^2+a)]*1/[a（a-2b）]=ab(a+2b)/(b^2+a)将a=-2,b=...