Question

[(x+2y)的平方-(x+y)(x-y)-5y的平方]除以(2x)

Answer 1

x^2=x的平方 ‘/’为除以

[(x+2y)^2-(x+y)(x-y)-5y^2]/(2x)=[(x^2+4xy+4y^2)-(x^2-y^2)-5y^2]/(2x)

=[4xy]/(2x)=2y

[(3x+2y)(3x-2y)-(x+2y)(5x-2y)]/(4x)=[9x^2-4y^2-(5x^2-2xy+10xy-4y^2)]/(4x)

=(4x^2-8xy)/(4x)=x-2y

[(2x+y)^2-（-y+2x）(y+2x)]/(2y)=[4x^2+4xy+y^2-(4x^2-y^2)]/(2y)

=(4xy+2y^2)/(2y)=2x+y