Question

化简后求值 [(x-2y)²+(x-2y)(x-2y)-2x(2x-y)]÷2x 其中x=2 y=3

Answer 1

[[(x-2y)²+(x-2y)(x-2y)-2x(2x-y)]÷2x
=(x^2-4xy+4y^2+x^2-4xy+4y^2-4x^2+2xy)÷2x
=(-2x^2-6xy+8y^2)÷2x
=-x-3y+4y^2/x
=-2-9+18
=7
但我觉得原题可能是(x-2y)²+(x+2y)(x-2y)-2x(2x-y)]÷2x
那么
原式=(x-2y)²+(x+2y)(x-2y)-2x(2x-y)]÷2x
=(x^2-4xy+4y^2+x^2-4y^2-4x^2+2xy)÷2x
=(-2x^2-2xy)÷2x
=-x+y
=y-x
=3-2
=1