how come?
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Your post doesn't make sense. If X ∈ ℝ, then X is a real number. But your X is posted as a set--and an unclear one at that.
If you meant for X to be the ordered pair (column vector) (2, 2), then span(X) would be the line through the origin in IR² that passes through the point (2, 2).
The usual Cartesian representation of this line is y = x.
In general, if x = (a, b) is any vector in IR², the space span(x) = {kx | k ∈ ℝ} is either (1) The origin if a = b = 0, or (2) the line through the origin and through (a,b).
If you meant for X to be the ordered pair (column vector) (2, 2), then span(X) would be the line through the origin in IR² that passes through the point (2, 2).
The usual Cartesian representation of this line is y = x.
In general, if x = (a, b) is any vector in IR², the space span(x) = {kx | k ∈ ℝ} is either (1) The origin if a = b = 0, or (2) the line through the origin and through (a,b).