(x3+1)(x2+1\x)6展开式中x3项的系数为?(数字是次数)跪求详解

问题描述:

(x3+1)(x2+1\x)6展开式中x3项的系数为?(数字是次数)跪求详解

(x³+1)(x²+1/x)^6其中(x²+1/x)^6的通项是C(6,i)*(x²)^(6-i)*(1/x)^i=C(6,i)*x^(12-3i)令12-3i=0得i=4所以常数项是C(6,4)=15令12-3i=3得i=3所以x³项是C(6,3)*x^(12-3*3)=20x³所以(x...