函数f(x)=(ax-6)/(x^2 +b)的图象在点M(-1,f(-1))处的切线方程为x+2y+5=0f(-1))=(-a-6)/(1+b) -1+2f(-1)+5=0 a=2b-4f(x）的导数为a/(x*x+b) -[2(ax-6)x]/(x*x+b)^2f(-1)的导数为 [2(-a-6)]/(1+b)^2=切线斜率-1/2化简...