A (non-empty) subset WW of VV is called a supspace of VV if for any x,y∈Wx,y∈W,
span ({x,y})⊆W span ({x,y})⊆W.
Note that this definition easily implies that:
-
0
∈
W
0
∈
W
- WW is itself a vector space
-
[No]
-
[Yes]
- V=R5V=R5, W={x:x4=0,x5=0}W={x:x4=0,x5=0} [Yes]
- V=R5V=R5, W={x:x4=1,x5=1}W={x:x4=1,x5=1} [No]
- V=C[0,1]V=C[0,1], W=W={polynomials of degree NN} [Yes]
- V=C[0,1]V=C[0,1], W={f:fW={f:f is bandlimited to BB} [Yes]
- V=RNV=RN, W={x:x hasnomorethan 5 nonzerocomponents ,i.e.,x0≤5}W={x:x hasnomorethan 5 nonzerocomponents ,i.e.,x0≤5} [No]