## Algebra and Trigonometry 10th Edition

$4\sqrt 5-1$ it is a scalar.
$||w||-1=\sqrt {w⋅w}-1=\sqrt {⟨−4,2⟩⋅⟨−4,2⟩}-1=\sqrt {-4(-4)+2(2)}-1=\sqrt {20}-1=4\sqrt 5-1$