What is the result of k(A+B)k(A+B)k(A+B) where kkk is a scalar?
kA+BkA + BkA+B
A+kBA + kBA+kB
kA+kBkA + kBkA+kB
k2A+k2Bk^2 A + k^2 Bk2A+k2B