The negative 1 factors in the product
Negative 1 times negative 1 is 1. Thus if there are negative 1 factors in a product, then the negative 1 factors cancel each other out in pairs.
Negative 1 times negative 1 is 1. Thus if there are negative 1 factors in a product, then the negative 1 factors cancel each other out in pairs.
Negative 1 times negative 1 is 1. Thus if there are negative 1 factors in a product, then the negative 1 factors cancel each other out in pairs.
Negative 1 times negative 1 is 1. Thus if there are negative 1 factors in a product, then the negative 1 factors cancel each other out in pairs.