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WAEC Further Mathematics 2022 Paper

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Question : 26

Total: 45

If →PQ = -2i + 5j and →RQ = -i - 7j, find →PR

-3i + 12j
-3i - 12j
-i + 12j
i - 12j

Solution:

Concept:

Use the triangle law of vector addition to connect

\overrightarrow{PQ}

,

\overrightarrow{PR}

, and

\overrightarrow{RQ}

.

Explanation:

Taking the path from

P

to

Q

through

R

:

\overrightarrow{PQ} = \overrightarrow{PR} + \overrightarrow{RQ}

So,

\overrightarrow{PR} = \overrightarrow{PQ} - \overrightarrow{RQ}

Substitute the given vectors:

\overrightarrow{PR} = (-2i + 5j) - (-i - 7j)

Simplify the signs:

\overrightarrow{PR} = -2i + 5j + i + 7j

Combine like terms:

\overrightarrow{PR} = (-2 + 1)i + (5 + 7)j

\overrightarrow{PR} = -i + 12j

Answer:

C.

-i + 12j

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