BECE Mathematics 2022 Paper

Concept:Reversing the direction of a vector means multiplying both components by $-1$.Explanation:Given $\overset{\rightarrow}{PQ} = \binom{-3}{8}$.The vector $\overset{\rightarrow}{QP}$ is the negative of $\overset{\rightarrow}{PQ}$.So, $\overset{\rightarrow}{QP} = -\overset{\rightarrow}{PQ}$.Multiply each component by $-1$:$\overset{\rightarrow}{QP} = \binom{-(-3)}{-8} = \binom{3}{-8}$.Key point: Reversing a vector changes the sign of both components, so $\binom{3}{8}$ (only the top sign changed) and $\binom{-3}{-8}$ (only the bottom sign changed) are traps.Answer:$\overset{\rightarrow}{QP} = \binom{3}{-8}$.Thus, the correct option is C.