25 - Direct sums of subspaces

26 - Linear combinations and spans

Two Subspaces of R^2 whose Union is not a Subspace

30 - Theorems about linear independence

24 - Intersections and sums of subspaces

Sums U+W and direct sums U⊕W of subspaces | definition, criterions, several examples

48 - Linear maps

Linear Algebra 130, Direct Sum

Independence, Basis, and Dimension

Oxford Linear Algebra: Direct Sum of Vector Spaces

33 - The dimension of a vector space

30. Linear Transformations and Their Matrices

External Direct Sums

Direct Sum of Subspaces (Theorem) | Vector Space | Linear Algebra

22 - Vector subspaces

23 - More examples of subspaces

Direct Sum of Subspaces and its Examples

1. The Geometry of Linear Equations

Linear subspaces | Vectors and spaces | Linear Algebra | Khan Academy