Let W be a subset of Rn What does it mean when we say that W

Let W be a subset of R^n. What does it mean when we say that W is closed under addition? Whenever X and Y are in R^n, then X + Y is in W. Whenever X and Y are in W, then X + Y is in W. Every vector in W is the sum of two vectors in W. If X + Y is in W, then X and Y are in W.

Solution

option b is correct.

W is closed under addition that is

whenever X and Y are in W, then X+Y is in W.