Let V be the vector space of all 2 × 2 matrices over R. Consider the subspaces
\(W_1 = \left\{ \left( \begin{matrix} a & -a \\\ c & d \end{matrix}\right) ; a, c, d \in R\right\}\)
and
\(W_2 = \left\{ \left( \begin{matrix} a & b \\\ -a & d \end{matrix}\right) ; a, b, d \in R\right\}\)
If m = dim(W1 ∩ W2) and n = dim(W1 + W2), then the pair (m, n) is
1
(2, 3)
2
(2, 4)
3
(3, 4)
4
(1, 3)