4x-[9x平方-2(5x-x平方)-1/2(8-2x)]得多少

问题描述:

4x-[9x平方-2(5x-x平方)-1/2(8-2x)]得多少

4x-[9x²-2(5x-x²)-1/2(8-2x)]
=4x-[9x²-10x+2x²-4+x]
=4x-[11x²-9x-4]
=-11x²+13x+4