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WAEC Mathematics 2018 Paper

Question : 7

Total: 50

\log_{10}

\log_{10}

2 = 1, solve for x.

Solution:

Concept:

Use the logarithm subtraction rule:

\log_b a - \log_b c = \log_b\left(\frac{a}{c}\right)

Explanation:

Given:

\log_{10}(6x-4)-\log_{10}2=1

Rewrite

1

\log_{10}10

, because

\log_{10}10=1

So,

\log_{10}(6x-4)-\log_{10}2=\log_{10}10

Combine the left side using the subtraction rule:

\log_{10}\left(\frac{6x-4}{2}\right)=\log_{10}10

Since both sides have the same base, equate the arguments:

\frac{6x-4}{2}=10

Multiply both sides by

2

6x-4=20

Add

4

to both sides:

6x=24

Divide both sides by

6

x=4

Answer:

x=4

Therefore, the correct option is C.

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