Find the Magnitude $\mathbf { u } = \langle - 1,2 \rangle$

Multiple Choice

Find the magnitude.
-Let $\mathbf { u } = \langle - 1,2 \rangle$ . Find the magnitude (length) of the vector: $7 \mathbf { u }$ .

A) $7 \sqrt { 10 }$
B) $- 7 \sqrt { 5 }$
C) $7 \sqrt { 5 }$
D) $\sqrt { 10 }$