Step-by-step explanation:
[tex]\text{Put}\ n=1,\ n=2,\ n=3,\ n=4\ \text{and}\ n=5\ \text{to the sum:}\\\\\sum\limits_{n=1}^5(2n+1)=(2(1)+1)+(2(2)+1)+(2(3)+1)+(2(4)+1)+(2(5)+1)\\\\=2+1+4+1+6+1+8+1+10+1=35[/tex]
