Simplify this. √7+3√7?

Question

I need help on my summer math packet i still dont understand how to simplify this.

√7+3√7

Answer 1

sqrt(7) +3sqrt(7)= (1+3)sqrt(7)=4sqrt(7)

Answer 2

Okay, so set √7=a (thats a^2=7 for a>0) to make the expression:

a+3a=a(1+3)=a(4)=4a

Now, input a=√7 to get:

4a=4√7

Peace

Answer 3

You know that x + 3x = 4x.  The same principle applies when it comes to adding up multiples of the same radical.  So it's:

4√7