<p>设实对称矩阵<img alt="" width="147" height="149" class="doc-27e6-eba6-821d-e152 " src="https://learnfile.20230611.cn/learnAppQuestion/18/e4/18e4de7ca44f98dc8a5b578ce1932ab4.png" style="width: 100%;height: auto;">，则3元二次型<img alt="" width="144" height="33" class="doc-eba6-821d-e152-ced0 " src="https:// - 线性代数（经管类）(04184)