Let \(u\) = (5, -12) and \(c\) = -3. What is ||\(cu\)||?
a) 21
b) -39
c) 51
d) 39
cu = -3 ( 5 , -12) = ( -15 , 36)
ll cu ll = sqrt [ (-15)^2 + 36^2 ] = sqrt (1521) = 39
