WAEC 2015 Mathematics · Question 3

If 2n = y, Find 2(2+n3)^{(2 + \frac{n}{3})}

Options

  1. A.4y13^\frac{1}{3}
  2. B.4y−3^-3
  3. C.2y13^\frac{1}{3}
  4. D.2y−3^-3

Answer: A. 4y13^\frac{1}{3}

Explanation written with AI and checked against the answer key

Analyze the question: The statement "2n = y" is most likely a typing error for 2^n = y (the original WASSCE question is 2^n = y). We need to find 2^(2 + n/3) in terms of y.

If it literally meant 2n = y, then n = y/2 and the answer would be 2^(2 + y/6), which matches none of the options. So the intended condition is 2^n = y.

Concept: Laws of indices:

  • a^(m+n) = a^m × a^n
  • a^(mn) = (a^m)^n

Solution:

2^(2 + n/3) = 2² × 2^(n/3)

Now 2^(n/3) = (2^n)^(1/3) = y^(1/3)

So:

2^(2 + n/3) = 4 × y^(1/3) = 4y^(1/3)

Tip: When you see a sum in the power, split it into a product of separate powers. When you see a fraction in the power, rewrite it as a root of the known expression. Here, 2^(n/3) is just the cube root of 2^n.

AI can make mistakes. Report anything that looks wrong.

Past questions © the examination body (JAMB/WAEC/NECO). DeeepSolve is not affiliated with them. Rights holders: see /copyright.