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WAEC Mathematics 2017 Paper

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Question : 8

Total: 49

Solve the equation:

\;\frac{1}{5x} + \;\frac{1}{x}

= 3

$\;\frac{1}{5}$
$\;\frac{2}{5}$
$\;\frac{3}{5}$
$\;\frac{4}{5}$

Solution:

Concept:

Rewrite both fractions with a common denominator and then solve the linear equation for

x

.

Explanation:

\frac{1}{5x}+\frac{1}{x}=3

Write

\frac{1}{x}

as

\frac{5}{5x}

.

So,

\frac{1}{5x}+\frac{5}{5x}=3

.

This gives

\frac{1+5}{5x}=3

.

Therefore,

\frac{6}{5x}=3

.

Multiplying both sides by

5x

, we get

6=15x

.

Divide both sides by 15:

x=\frac{6}{15}

.

Simplify:

x=\frac{2}{5}

.

Answer:

x=\frac{2}{5}

Correct option: B.

\frac{2}{5}

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