Question

已知x=根号5-根号3/2,y=根号5+根号3/2, 求代数式x的平方-3xy+y的平方的值

Answer 1

x^2-3xy+y^2

=(x-y)^2-xy

=[√5-√3/2-(√5+√3/2)]^2-(√5-√3/2)(√5+√3/2)

=(-√3)^2-(5-3/4)

=3-17/4

=-29/4