Question

那已知x+y=10,xy=-2,求(x-y)的平方的值

Answer 1

(x+y)^2=100
(x-y)^2=100-4xy=100+8=108

Answer 2

(x+y)2=x2+2xy+y2=100 (x-y)2+4xy=100 (x-y)2-8=100 (x-y)2=108 x-y=6倍的根号三

Answer 3

52加减根号27