若mρcos²θ+3ρsin²θ-6cosθ是椭圆,求m范围

问题描述:

若mρcos²θ+3ρsin²θ-6cosθ是椭圆,求m范围

应该是mρcos²θ+3ρsin²θ-6cosθ=0是椭圆吧.两边都乘以ρ,得mρ²cos²θ+3ρ²sin²θ-6ρcosθ=0也即:mx²+3y²-6x=0变形得(x-3/m)²/(9/m²)+y²/(3/m)=1要使...