Question

x(y-1)-y(x-1)=4求x平方加y平方等于几?

Answer 1

题目肯定有问题,不用纠结了.

条件x(y-1)-y(x-1) = 4可等价的写为y-x = 4.

但是对于满足y-x = 4的x,y,x²+y²可以有无穷多种取值.

例如x = 1,y = 5满足条件,相应x²+y² = 26.

而x = 2,y = 6也满足条件,相应x²+y² = 40.

再来x = 3,y = 7满足条件,相应x²+y² = 58.

一般的x²+y² = x²+(x+4)² = 2x²+8x+16,随x的变化可以有无穷多种取值.