Linear combination
Given vectors u1,u2,...,um in Rn and scalars k1,k2,...,km in R, the linear combination is a vector $$ v = k_1 u_1 + k_2 u_3 + ... + k_m v_m $$
Linear combination is the sum of the scalar products.
Example
Given 2 vectors in R3
$$ u_1 = \begin{pmatrix} 1 \\ 2 \\ 1 \end{pmatrix} $$
$$ u_2 = \begin{pmatrix} 3 \\ -1 \\ 2 \end{pmatrix} $$
and 2 scalars in R
$$ k_1 = 3 $$
$$ k_2 = -1 $$
The linear combination is a vector v such as
$$ v = k_1 u_1 + k_2 u_2 $$
$$ v = 3 \cdot u_1 + (-1) \cdot u_2 $$
$$ v = 3 \cdot \begin{pmatrix} 1 \\ 2 \\ 1 \end{pmatrix} + ( -1 ) \cdot \begin{pmatrix} 3 \\ -1 \\ 2 \end{pmatrix} $$
$$ v = \begin{pmatrix} 3 \cdot 1 \\ 3 \cdot 2 \\ 3 \cdot 1 \end{pmatrix} + \begin{pmatrix} ( -1 ) \cdot 3 \\ ( -1 ) \cdot (-1) \\ ( -1 ) \cdot 2 \end{pmatrix} $$
$$ v = \begin{pmatrix} 3 \\ 6 \\ 3 \end{pmatrix} + \begin{pmatrix} -3 \\ 1 \\ -2 \end{pmatrix} $$
$$ v = \begin{pmatrix} 3 + (-3) \\ 6 + 1 \\ 3 + (-2) \end{pmatrix} $$
$$ v = \begin{pmatrix} 0 \\ 7 \\ 1 \end{pmatrix} $$