已知:x-2y=3,求[(3x+2y)(3x-2y)-(x+2y)(5x-2y)]除1/3

问题描述:

已知:x-2y=3,求[(3x+2y)(3x-2y)-(x+2y)(5x-2y)]除1/3
等于36x吗

[(3x+2y)(3x-2y)-(x+2y)(5x-2y)]除1/3
=[9x²-4y²-5x²-8xy+4y²)×3
=(4x²-8xy)×3
=12x(x-2y)
=36x我对了