Question

Let u = <-5, -9>, v = <6, 8>. Find -8u - 2v.

Answer 1

$\vec{u}=[-5;-9]\\\vec{v}=[6;\ 8]\\\\-8\vec{u}-2\vec{v}=-8\cdot[-5;-9]-2\cdot[6;\ 8]\\\\=[(-9)(-5);(-8)(-9)]-[(2)(6);\ (2)(8)]\\\\=[40;\ 72]-[12;\ 16]=[40-12;\ 72-16]\\\\=\boxed{[28;\ 56]}$

Answer 2

If u and v are indeed vectors,
$- 8u - 2v = - 8( - 5, - 9) - 2(6,8) \\ = (40,72) - (12,16) \\ = (28,56)$
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