Question

椭圆9x+4y＝1的焦点坐标

Answer 1

椭圆9x^2+4y^2＝1

a^2=1/4 b^2=1/9 (注意要a>b)

c^2=a^2-b^2=(9-4)/36=5/36

所以焦点坐标是(0,-√5/6)和(0,√5/6)