Question 214682
You are correct.  However:
.
Sqrt(7a)+6sqrt(63a^3)
Sqrt(7a)+6sqrt(9*7*a^2*a)
Sqrt(7a)+6*3sqrt(7a)--forgot the leading 'a' should be:
Sqrt(7a)+6*3*a*sqrt(7a)
=(1+18a)Sqrt(7a)