q-二项式定理 要线性求出下面式子的每一项: F ( x ) = ∏ i = 1 n ( 1 + q i x ) F(x)=\prod_{i=1}^{n}(1+q^ix) F(x)=i=1∏n(1+qix) 显然有: F ( q x ) ( 1 + q x ) = F ( x ) ( 1 + q n + 1 x ) F(qx)(1+qx)=F(x)(1+q^{n+1}x) F(qx)(1+qx)=F(x)(1+qn+1x) 设 F ( x ) = ∑ i = 0 n