3x-2y-4=0.(1)
2x+y-5=0.(2)
2*(2):
4x+2y-10=0.(3)
(3)+(1):
7x-14=0
x=2
y=5-2x=5-4=1
r^2=[2-(-1)]^2+1=10
圆的方程:(x+1)^2+y^2=10