Answer
$|\overrightarrow{u}|=5$;
$\overrightarrow{u} \cdot \overrightarrow{u}=25$;
$\overrightarrow{u} \cdot \overrightarrow{v}=60$
Work Step by Step
Here, we have $u=(4,-3); v=(9,-8)$
$|\overrightarrow{u}|=\sqrt {(4)^2+(-3)^2}=\sqrt {25}=5$;
$\overrightarrow{u} \cdot \overrightarrow{u}=(4)^2+(-3)^2=25$;
$\overrightarrow{u} \cdot \overrightarrow{v}=4(9)+(-3)(-8)=36+24$
or, $\overrightarrow{u} \cdot \overrightarrow{v}=60$
