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WAEC Further Mathematics 2016 Paper

Question : 11

Total: 40

5^{x} \times 5^{x + 1} = 25

Solution:

Concept:

Use the law of exponents:

a^m \times a^n = a^{m+n}

. Then equate the powers since the bases are equal.

Explanation:

Rewrite

25

as a power of

5

25 = 5^2

So,

5^{x} \times 5^{x+1} = 5^2

Combine the left-hand side using the exponent law:

5^{x + (x+1)} = 5^2

This gives

5^{2x+1} = 5^2

Since the bases are the same, equate the exponents:

2x + 1 = 2

Subtract

1

from both sides:

2x = 1

Therefore,

x = \frac{1}{2}

Answer:

x = \frac{1}{2}

, which is option C.

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