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 is C

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  \(\frac{√21}{3}\)