求y=[sinx+3(√3)cosx]/(sinx cosx)的最值.y=1/cosx+3(√3)/sinx令y′=sinx/cos²x-3(√3)cosx/sin²x=0得sin³x-3(√3)cos³x=0,故得tan³x=3√3,tanx=√3,于是得驻点x=π/3+kπ当k是偶数时,x=...