Use algebraic manipulation to show that for three input varibles x1, x2, and x3
$$\sum$$m(1,2,3,4,5,6,7) = x1 + x2 + x3
So far all I have is a truth table with 8 rows because I know 2^3 = 8 (starting at 0 of course, just assume the list I prepared on here is starting at 0 and not 1 - ending...