Question 181253
I'm sorry to be so late answering this, but I thought it was a nice question, and I didn't see it earlier.  If you have other questions about square roots and their operations, check out my website by clicking on my tutor name "rapaljer" anywhere in algebra.com, on my Homepage find the link that says "Basic, Intermediate, and College Algebra: One Step at a Time."  Then select "Basic Algebra" and go to Chapter 5.  The whole explanation is there written so ordinary folks can understand it.  At least that's what my students tell me!!  Best of all, it's all FREE!  


Now, here is your problem and solution:


sqrt75 - sqrt12 + sqrt3 = 5 sqrt3 - 2 sqrt3 + sqrt3 = 3 sqrt3


This is just like combining like terms, but I think you should have ended up with 4 sqrt3.  I explain it like this.  If it had been "cats" instead of square root of 3, you would have had 

5 cats - 2 cats + cat = 3 cats + cat = 4 cats


If it had been x terms instead of square root of 3 or instead of "cats", it would have looked like this:  
5 x - 2x + x = 3x + x = 4x



So you are correct in what you said about the invisible 1:

sqrt75 - sqrt12 + sqrt3 

= 5 sqrt3 - 2 sqrt3 + sqrt3 

= 3 sqrt3 + 1 sqrt3 
= 4 sqrt3


R^2