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WAEC Mathematics 2013 Paper

Question : 12

Total: 48

\;\frac{1}{2}

\;\frac{3}{2}

x - 2y = 1, find (x + y)

Solution:

Concept:

Solving two linear equations using the elimination method, then substituting to find the required value.

Explanation:

Given equations:

\frac{1}{2}x + 2y = 3

... (i)

\frac{3}{2}x - 2y = 1

... (ii)

Add equations (i) and (ii) to eliminate

y

\left(\frac{1}{2}x + \frac{3}{2}x\right) + (2y - 2y) = 3 + 1

This gives:

2x = 4

x = \frac{4}{2} = 2

Substitute

x = 2

into equation (i):

\frac{1}{2}(2) + 2y = 3

1 + 2y = 3

2y = 3 - 1 = 2

y = \frac{2}{2} = 1

Now calculate

x + y

x + y = 2 + 1 = 3

Answer:

x + y = 3

, so the correct option is A.

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