1. Adding and subtracting radicals. Add 3√21 + 7√21
A. √24 + √28
B. √52
C. 10√42
D. 10√21
I have a feeling its d
You are correct!
To add the radicals, you add the coefficients and keep the same radical. So, 3√21 + 7√21 = (3+7)√21 = 10√21.
Therefore, the correct answer is D. 10√21.