a1x+b1y=c1

a2x+b2y=c2

x=(c1b2-c2b1)/(a1b2-a2b1)

y=(c1a2-c2a1)/(b1a2-b2a1)

当a1b2-a2b1=0,c1b2-c2b1=0时,解为一切实数