第一式乘以2加第二式得3x^2=21x^2=7代入第一式得y^2=6x=正负根号7y=正负根号6
x^2-y^2=1 (1)x^2+2y^2=10 (2)(2)-(1)得,3y^2=9 -> y^2=3 -> y=±√3x^2=1+y^2=4 -> x=±2
