Walk At Home

Is there a formal proof for $(-1) \\times (-1) = 1$? It's a fundamental formula not only in arithmetic but also in the whole of math. Furthermore, Intending on marking as accepted, because I'm no mathematician and this response makes sense to a commoner. Moreover, 注1：【】代表软件中的功能文字 注2：同一台电脑，只需要设置一次，以后都可以直接使用 注3：如果觉得原先设置的格式不是自己想要的，可以继续点击【多级列表】——【定义新多级列表】，找到相应 …. In related context, What is the expansion for $(1-x)^{-n}$? Could find only the expansion upto the power of $-3$. These findings regarding Walk At Home provide comprehensive context for understanding this subject.