已知X+y=10,XY=24,求(X-Y)(X-Y)的值

X+y=10,XY=24,则X=4，Y=6或X=6，Y=4，
所以(X-Y)(X-Y)=2*2=4或（-2）*（-2）=4，都为4

X+y=10,XY=24
x=6,y=4,或者x=4,y=6
当x=6,y=4
(X-Y)(X-Y)=36-16=20
当x=4,y=6
(X-Y)(X-Y)=16-36=-20

所以(X+Y)^2=100
所以(X-Y)^2=(X+Y)^2-4XY=100-24*4=100-96=4
^2为谁的平方

(X-Y)(X-Y)=X^2+Y^2-2XY=(X+Y)^2-4XY=100-96=4

(X-Y)(X-Y)=(x+Y)的平方-4XY=100-4x24=100-96=4