已知x^2+y^2-4x+y+4又1/4=0,求x^2+9y^2

已知x^2+y^2-4x+y+4又1/4=0,求x^2+9y^2
已知x^2+y^2-4x+y+4又1/4=0,求x^2+9y^2

已知x^2+y^2-4x+y+4又1/4=0,求x^2+9y^2
x^2+y^2-4x+y+4又1/4=0
(x-2)²+(y+1/2)²=0
∴ x=2,y=-1/2
x²=4
9y²=9*1/4
x²+9y²=4+9/4=25/4

由已知 x^2+y^2-4x+y+5/4=0 得 （x-2)^2+(y+1/2)^2=0 x=2 y=-1/2
故 x^2+9y^2=4+9*1/4=25/4