Question

Shortern this expression pls​

Answer 1

Answer:

$c =\frac{8}{3}$

Step-by-step explanation:

Given

$c = \sqrt{\frac{4 + \sqrt 7}{4 - \sqrt 7}} + \sqrt{\frac{4 - \sqrt 7}{4 + \sqrt 7}}$

Required

Shorten

We have:

$c = \sqrt{\frac{4 + \sqrt 7}{4 - \sqrt 7}} + \sqrt{\frac{4 - \sqrt 7}{4 + \sqrt 7}}$

Rationalize

$c = \sqrt{\frac{4 + \sqrt 7}{4 - \sqrt 7} * \frac{4 + \sqrt 7}{4 + \sqrt 7}} + \sqrt{\frac{4 - \sqrt 7}{4 + \sqrt 7}*\frac{4 - \sqrt 7}{4 - \sqrt 7}}$

Expand

$c = \sqrt{\frac{(4 + \sqrt 7)^2}{4^2 - (\sqrt 7)^2}} + \sqrt{\frac{(4 - \sqrt 7)^2}{4^2 - (\sqrt 7)^2}$

$c = \sqrt{\frac{(4 + \sqrt 7)^2}{16 - 7}} + \sqrt{\frac{(4 - \sqrt 7)^2}{16 - 7}$

$c = \sqrt{\frac{(4 + \sqrt 7)^2}{9}} + \sqrt{\frac{(4 - \sqrt 7)^2}{9}$

Take positive square roots

$c =\frac{4 + \sqrt 7}{3} + \frac{4 - \sqrt 7}{3}$

Take LCM

$c =\frac{4 + \sqrt 7 + 4 - \sqrt 7}{3}$

Collect like terms

$c =\frac{4 + 4+ \sqrt 7 - \sqrt 7}{3}$

$c =\frac{8}{3}$