阅读下列计算过程:4x²+2x-1-kx²+3x+2=(4-k)x²+5x+1阅读下列计算过程:4x²+2x-1-kx²+3x+2=(4-k)x²+5x+1所以要使上式中不含有二次项,只需满足4-k=0,即k=4即可.当k取何值时,2x²y-[3xy²-2(xy-kx²y)+3xy]+3xy²中不含有三次项.

问题描述:

阅读下列计算过程:4x²+2x-1-kx²+3x+2=(4-k)x²+5x+1
阅读下列计算过程:4x²+2x-1-kx²+3x+2=(4-k)x²+5x+1
所以要使上式中不含有二次项,只需满足4-k=0,即k=4即可.当k取何值时,2x²y-[3xy²-2(xy-kx²y)+3xy]+3xy²中不含有三次项.

去括号:2x²y-3xy²+2xy-2kx²y-3xy+3xy²
整理:2-2k=0
k=1

K=1

2x²y-[3xy²-2(xy-kx²y)+3xy]+3xy²=2x²y-3xy²+2xy-2kx²y-3xy+3xy²=2x²y-2kx²y-xy因为不含3次项,因此2x²y-2kx²y=0因此2k=2因此k=1