Proving Standard Inner Function Property 3

Proof

Calculate $⟨u_1,cv⟩$ $=⟨(u_1,\dots ,u_n),(c{v}_1,\dots ,c{v}_n)⟩$ $={\sum }_{k=1}^n(u_i)(c{v}_i)$ $=c{\sum }_{i=1}^n{u}_i{v}_i$ $=c⟨u_1,v⟩$