Answer
$\lt 10,-25 \gt$ and $5 \sqrt {29}$
Work Step by Step
The formula to find the magnitude of a vector is:
$|n|=\sqrt{n_1^2+n_2^2}$
Here, $5v=5\lt 2,-5 \gt =\lt 10,-25 \gt$
and $|\lt 10,-25\gt|=\sqrt{(10)^2+(-25)^2}=\sqrt {725}=5 \sqrt {29}$
Hence, our final answers are: $\lt 10,-25 \gt$ and $5 \sqrt {29}$
