Question

simplify Radical 5x+21=radical 6

possible answers
x=-3
x=3
x=11
none of the above

Answer 1

1. Remove Radical by taking square of both sides
2. Solve for x

Answer 2

Please use parenthesis...

It's either one of these depending on what the radical is:
\[\sqrt{5 x+21} = \sqrt{6}\]
\[5 x+21 = 6 \]
\[5x = -15\]
\[x=-3\]

OR

\[\sqrt{5x}+21 = \sqrt{6}\]
\[\sqrt{5} * \sqrt{x}+21 = \sqrt{6}\]
\[ \sqrt{x} = \sqrt{\frac{6}{5}}-\frac{21}{\sqrt{5}} \]
\[x = \frac{447-42 \sqrt(6)}{5} \]

Answer 3

You chose based on what you meant, both of those are correct depending on what is having a squareroot of (5x) or (5x+21), and it makes a BIG difference as you can see.