Test Index

JAMB Mathematics 2013 Paper

© africaexams.com

Question : 5

Total: 47

Simplify

\frac{3^{-5n}}{9^{1-n}} \times 27^{n+1}

3²
3³
3⁵
3

Solution:

Concept:

Express all numbers as powers of

3

, then apply the laws of indices.

Explanation:

Write

9 = 3^2

and

27 = 3^3

.

So the expression becomes:

\frac{3^{-5n}}{3^{2(1-n)}} \times 3^{3(n+1)}

Combine the powers by adding the exponents:

3^{-5n - 2(1-n) + 3(n+1)}

Simplify the exponent:

-5n -2 + 2n + 3n + 3

Collect like terms:

(-5n + 2n + 3n) + (-2 + 3)

This gives:

0n + 1 = 1

Therefore, the expression equals:

3^1 = 3

Answer:

3

(Option D)

© africaexams.com

Go to Question:

Prev Question

Next Question