To find ||v|| we can use the following formula:
[tex]||v||=\sqrt{a^2+b^2}[/tex]
Where a and b are the coordinates of the vector. Replace a for 5 and b for -8:
[tex]\begin{gathered} ||v||=\sqrt{5^2+(-8)^2} \\ ||v||=\sqrt{25+64} \\ ||v||=\sqrt{89} \\ ||v||=9.43 \end{gathered}[/tex]
Now, substract 3 from ||v||:
[tex]||v||-3=6.43[/tex]
The answer is 6.43.
