tangent line For what values of a and b is the line 4x+y=b tangent to the curve y=ax^3 when x=5?
问题描述：
tangent line For what values of a and b is the line 4x+y=b tangent to the curve y=ax^3 when x=5?
求详细解答
答
Assume a and b are constants4x+y=by=b-4xgradient(m)=-4y=ax³dy/dx=3ax²since line is tangent to curve,3ax²=-4when x=5,3a(5)²=-4a=-4/75y=(-4/75)(5)³=-20/34x+y=b4(5)+(-20/3)=bb=40...