已知(4,3)是抛物线x=ay^2+by(a>0)的焦点,求a,b值

已知(4,3)是抛物线x=ay^2+by(a>0)的焦点,求a,b值
已知(4,3)是抛物线x=ay^2+by(a>0)的焦点,求a,b值

已知(4,3)是抛物线x=ay^2+by(a>0)的焦点,求a,b值
设x' = x-4
则 x' = ay^2+by+4的焦点为(0,3),设其焦距为|p|,
则 x' = 2p(y-p+3)^2
故 a = 2p
b = 2p(2*(3-p))
4 = 2p(3-p)^2
解方程得 p=2,a=4,b=8