a)

std(x1) = sqrt(9) = 3

std(x2) = sqrt(1) = 1

corr(x1, x2) = 0/3 = 0

b)

std(x1) = sqrt(1) = 1

std(x2) = sqrt(1) = 1

corr(x1, x2) = -.75/1 = -.75 → Negative Correlation

a) q < 0

b) q = 0

c) q^2 = p * r where q =/= 0

d) r = 0 & q = 0 because the variance must be 0 so r and q must both be 0.

The unit vector in the same direction (1, 2, 3)

= x / ||x||