Add 3√ 21 + 7√ 21√ .(1 point) Responses 24√ + 28√ Start Root 24 End Root plus Start Root 28 End Root 1021−−√ 10 Start Root 21 End Root 1042−−√ 10 Start Root 42 End Root 52−−√

Answer 1

To simplify the expression \( 3\sqrt{21} + 7\sqrt{21} \), you can combine the terms since they have a common square root.

1. Combine the coefficients: \[ 3\sqrt{21} + 7\sqrt{21} = (3 + 7)\sqrt{21} = 10\sqrt{21} \]

So, the simplified expression is:

\[ 10\sqrt{21} \]

Thus, the correct answer is \( 10\sqrt{21} \).