I'm able to find the minimum and maximum values for the norm of the sum of two vectors using the triangle inequality, but I'm not sure if I can find the exact value without knowing the angle between the vectors.
The following information is given: $\quad\bar v , \bar w \in \Bbb R^n, \quad \Vert \bar v \Vert =2, \quad \Vert \bar w \Vert =3, \quad \bar v \cdot \bar w =-1$ (dot product).
Find $\Vert \bar v + 2\bar w \Vert$.
Any help would be appreciated!