已知x-y=3xy,且xy不等于0,则-3x+6xy+3y/(7x-5y)-9xy-(3x-y)

问题描述:

已知x-y=3xy,且xy不等于0,则-3x+6xy+3y/(7x-5y)-9xy-(3x-y)

因为,x - y = 3xy 所以:-3x+6xy+3y/[(7x-5y)-9xy-(3x-y)]= [-3(x-y)+6xy]/[(7x-5y) - 9xy - (3x-y)]= [ -3*3xy + 6xy]/ [ 7x - 5y - 9xy - 3x + y] = -3xy/ [ 4x -4y -9xy]= -3xy/[4(x-y)-9xy]= -3xy/[4*3xy-9xy]= ...