202

a)
\left|\overline{u}\right|^2=3^2+4^2
\left|\overline{u}\right|^2=25\ \parallel\sqrt{ }
\left|\overline{u}\right|=5\ \left(tai\ -5\right)
\overline{u}^0=\frac{\overline{u}}{\left|\overline{u}\right|}
\overline{u}^0=\frac{3\overline{\text{i}}-4\overline{\text{j}}}{5}=\frac{3}{5}\overline{\text{i}}-\frac{4}{5}\overline{\text{j}}
b)
\overline{v}=-15\overline{u}^0=-15\cdot\left(\frac{3}{5}\overline{\text{i}}-\frac{4}{5}\overline{\text{j}}\right)=-9\overline{\text{i}}+12\overline{\text{j}}
c)