求满足X^3+Y^3+Z^3=9且X+Y+Z=3的所有整数解
问题描述:
求满足X^3+Y^3+Z^3=9且X+Y+Z=3的所有整数解
答
x^3+y^3+z^3=(x+y+z)(x^2+y^2+z^2-xy-yx-xz)+3xyz9=3*1/2[(x-y)^2+(x-z)^2+(y-z)^2]+3xyz(x-y)^2+(x-z)^2+(y-z)^2=6-2xyz6以内的完全平方数有0,1,4则(x-y)^2+(x-z)^2+(y-z)^2=1+1+4 xyz=0 x,y,z=1,2,00+0+4 xyz=1舍1...