Question

how to add inside a square root
$\sqrt{(270 - 120)(270 - 170)(270 - 250}$

Answer 1

Just like you would outside. As long as it is completely under the root, all operators work the same way
√ (270 - 120) (270 - 170) (270 - 250)
√ 150 * 100 * 20
√ 300000