设<img class="jc-formula" data-tex="AB=A+2B,B=\left( \begin{ matrix } 1 1 0 \\ -1 2 0 \\ 0 0 -1 \end{ matrix } \right) " src="https://huaweicloudobs.ahjxjy.cn/D2F461A75F7A9F59691FA3E4BBE8CA48.png" style="vertical-align: middle;"/>,求<img class="jc-formula" data-tex="A" src="https://huaweicloudobs.ahjxjy.cn/53F870B8D448BB3DB08A67264B6329F9.png" style="vertical-align: middle;"/>