Question

Find the indicatedquantity, given u = (-5, -9), v = (5, -8).Step 2 of 4 : Find 3u • v.

Answer 1

Given:

$\begin{gathered} u\text{ = \lparen-5, -9\rparen} \\ v\text{ = \lparen5, -8\rparen} \end{gathered}$

Required: 3u .v

$\begin{gathered} =\text{ 3u . v} \\ =\text{ 3\lparen-5,-9\rparen. \lparen5, -8\rparen} \\ =\text{ \lparen-15, -27\rparen. \lparen5, -8\rparen} \\ =\text{ -15 }\times\text{ 5 +}(-27\times-8) \\ =\text{ -75 + 216} \\ =\text{ 141} \end{gathered}$

Answer: 141