方程:x^2-y^2=1997的整数解

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方程:x^2-y^2=1997的整数解

方程:x^2-y^2=1997的整数解
方程:x^2-y^2=1997的整数解

方程:x^2-y^2=1997的整数解
(1)x=999,y=998,(2)x=-999,y=-998
(3)x=999,y=-998,(4)x=-999,y=998
1997是素数,故1997仅有分解式1997=1997*1
由x^2-y^2=1997得
(x+y)(x-y)=1997*1
故有4种情况:
(1)x+y=1997
x-y=1
得x=999
y=998
(2)x+y=-1997
x-y=-1
得x=-999
y=-998
(3)x-y=1997
x+y=1
x=999
y=-998
(4)x-y=-1997
x+y=-1
x=-999
y=998

x^2-y^2=1997
(x+y)(x-y)=1997*1
x=999,y=998
x=999,y=-998