use the summation symbol to write each sum in sigma notation
35+48+63+80+99
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[tex] \bf \stackrel{6^2-1}{35}~~+~~\stackrel{7^2-1}{48}~~+~~\stackrel{8^2-1}{63}~~+~~\stackrel{9^2-1}{80}~~+~~\stackrel{10^2-1}{99}
\\\\\\
~~~~~~~~~~~~~~~~~~ \sum\limits_{i=6}^{10}~i^2-1 [/tex]