关于二次根式当x=4-根号2,y=4+根号2时,(1)求根号下x^2-2xy+y^2 (2)求xy^2+x^2y的值

问题描述:

关于二次根式
当x=4-根号2,y=4+根号2时,(1)求根号下x^2-2xy+y^2 (2)求xy^2+x^2y的值

x^2-2xy+y^2
=(x-y)^2
=8
xy^2+x^2y
=xy(x+y)
=8*(4-根号2)(4+根号2)
=8*(4^2-根号2 ^2)
=8*14
自己算吧

x^2-2xy+y^2
=(x-y)^2
=(2*根号2)^2
=8
xy^2+x^2y
=xy(x+y)
=14*8
=112

1.
x^2-2xy+y^2 = (x-y)^2 = 8
所以根号下的x^2-2xy+y^2就是根号8,即2根号2
2.
xy^2+x^2y = xy(x+y)
xy = 16-2 = 14
x=y = 8
所以 xy^2+x^2y = xy(x+y) = 14*8 = 112

X根号下x^2-2xy+y^2
=Y-X=2根号2
2)xy^2+x^2y
=xy(x+y)
=14*8
=112