NECO 2001 Mathematics · Question 21
Simplify
Options
- A.± 16a
- B.± 16a
- C.± 14a
- D.± 12a
- E.± 12a
Answer: D. ± 12a
Explanation written with AI and checked against the answer key
Step 1: Analyze the question We need to multiply two square roots and simplify. The expressions inside are 6a⁻² and 24a⁶.
Step 2: Concept √x × √y = √(xy), and when we take a square root, the result is ± (positive or negative).
Step 3: Solution
Combine under one root:
√(6a⁻²) × √(24a⁶) = √(6 × 24 × a⁻² × a⁶)
- 6 × 24 = 144
- a⁻² × a⁶ = a^(−2+6) = a⁴
So we have:
√(144a⁴) = ±12a²
(Since √144 = 12 and √(a⁴) = a².)
Step 4: Answer The result is ±12a², which is option D.
Tip: When multiplying roots, combine them first, then multiply the numbers and add the powers of the same base. Halve the index at the end to take the square root (a⁴ → a²). Don't forget the ± sign when the question uses it in the options!
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