摘要：形式 $$ \sum_{i=1}^{n}a_i^2 \sum_{i=1}^{n}b_i^2 \geq \sum_{i=1}^{n}a_i^{2}b_i^2 $$ 等号成立的条件： $$ iff:b_i=0 || \exists k \in \mathbb {R},a_i=k \cdot b_i(i 阅读全文