simplify r+3+r^2+2r and explain why

Question

I don understandthis problem I failed in a tes but I don't know why.  

4r^2+3 tus was my answer.  Please help me. 

Answer 1

One way to think about it is to find the things that are really the same.  You added the "r" terms with the "r²" terms, which is like adding pears and bananas.   The only terms that are really the same are the "r" terms. 

 

r + 3 + r² + 2r 

 

Those are the same, so you can add them together. 

r²+3+3r

 

You can rearrange them and see if there is anything else to do.

r²+3r+3

 

Which there isn't so you're done.