Question

Find the dot product between the vectors u and v: u=2i+3j and v=-6i-5j

Answer 1

`\bf \stackrel{\textit{dot product}}{<a,b>\cdot <c,d>}\implies (a\cdot c)+(b\cdot d) \\\\[-0.35em] ~\dotfill\\\\ \begin{cases} u=&2i+3j\\ v=&-6i-5j \end{cases}\implies \begin{cases} <2,3>\\ <-6,-5> \end{cases} \\\\\\ <2,3>\cdot <-6,-5>\implies (2\cdot -6)+(3\cdot -5)\implies -27`