(d8−c)⋅(d−c8) = d(d) - d(c8) - c(d) + c(c8)= d^2 - d^2c - cd + c^2= d^2(1 - c) - c(1 - c)= d^2(1 - c) - c(1 - c)= d^2 - dc - c + c^2
(d8−c)⋅(d−c8) = d(d) - d(c8) - c(d) + c(c8)
= d^2 - d^2c - cd + c^2
= d^2(1 - c) - c(1 - c)
= d^2(1 - c) - c(1 - c)
= d^2 - dc - c + c^2