Simplify 2√7- 14/√7+7/√21
MATHEMATICS
WAEC 2021
Simplify 2√7- 14/√7+7/√21
- A. \(\frac{?21}{21}\)
- B. 7\(\frac{?21}{21}\)
- C. \(\frac{?21}{3}\)
- D. 3?21
Correct Answer: C. \(\frac{?21}{3}\)
Explanation
2√7- 14/√7 +7/√21
L.C.M is √21
\(\frac{√21 * 2√7 - √3 *14 + 7}{√21}\)
=\(\frac{2 * 7√3 - 14√3 + 7}{√21}\)
= \(\frac{14√3 - 14√3 + 7}{√21}\)
=\(\frac{7}{√21}\)
or
\(\frac{7 \times √21}{√21 \times √21}\)
= \(\frac{7 \times √21}{21}\) or \(\frac{√21}{3}\)
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