(x-4y)(x-y)-(x+3y)(x-6y)-5x(2-y),其中x=﹣1/3,y=1/2(x²-nx+3)(x²+3x+m)的展开式中不含x²和x³项,求m和 n的值

问题描述:

(x-4y)(x-y)-(x+3y)(x-6y)-5x(2-y),其中x=﹣1/3,y=1/2
(x²-nx+3)(x²+3x+m)的展开式中不含x²和x³项,求m和 n的值

原式=x²-5xy+4y²-x²+3xy+18y²-10x+5xy=3xy+22y²-10x=-1/2+11/2+10/3=25/3原式=x⁴+(3-n)x³+(m-3n+3)x²+(9-mn)x+3m不含则系数为0所以3-n=0,m-3n+3=0所以n=3m=3m-3=6...