6.1 Exercise 10

Three forces act on an object, considered to be a particle, which moves with constant velocity $v = \left(3 \hat{i} - 2 \hat{j}\right) \text{m}/\text{s} .$ Two of the forces are $\overset{\rightarrow}{F}_{1} = \left(3 \hat{i} + 5 \hat{j}\right) \text{N}$ and $\overset{\rightarrow}{F}_{2} = \left(4 \hat{i} - 7 \hat{j}\right) \text{N} .$ Find the third force.