Question

Which statement is true about the difference 2 square root of 7 − square root of 28 ?

Answer 1

I'll go slow:

$2\sqrt 7 - \sqrt{28}$

$=2 \sqrt 7 - \sqrt{4 \cdot 7}$

$=2 \sqrt 7 - \sqrt{4} \cdot \sqrt{7}$

$=2 \sqrt7 - 2 \sqrt 7$

$=0$

Answer: B  rational and equal to 0.