Given that r={-3}{4} and s={1}{-3}, find r-2s.

Correct Answer is : (−510)\; \; {-5}{10}(10−5)

Correct Answer is : (−510)\; \; {-5}{10}(10−5)

Test Index

BECE Mathematics 2012 Paper

Question : 27

Total: 40

Given that

r=\binom{-3}{4}

s=\binom{1}{-3}

r-2s

Solution:

Concept:

A vector can be multiplied by a scalar and then subtracted from another vector by performing the operation component-wise.

Explanation:

We are given

r=\binom{-3}{4}

and

s=\binom{1}{-3}

We need to compute

r-2s

First, multiply

s

2

2s=2\binom{1}{-3}=\binom{2}{-6}

Now subtract this from

r

r-2s=\binom{-3}{4}-\binom{2}{-6}

Subtract the corresponding components:

Top component:

-3-2=-5

Bottom component:

4-(-6)=4+6=10

Therefore,

r-2s=\binom{-5}{10}

This matches option B.

Answer:

r-2s=\binom{-5}{10}

(Option B).

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