use mathematical induction to prove the formula for every positive integer n.

3 + 5 + 7 + ... + (2n +1)= n(n +2)

this is a beastly problem.

i have proven that

n=1 so 2(1)+1=1(1)+2

3=3 so this works but now im dont know what to do next. i know im suppose to go further but im so lost. please help me understand this.