Final answer:
To add three and the square root of 21, and 7 and the square root of 21, you add the numbers and keep the square root of 21
Step-by-step explanation:
To add three and the square root of 21, you add 3 to the square root of 21. To add 7 and the square root of 21, you add 7 to the square root of 21. In both cases, the square root of 21 remains the same. So the final result is 3 + square root of 21 + 7 + square root of 21 = 10 + 2 times the square root of 21.
Learn more about Addition of numbers