Question

Fill in the blank

$\begin{array}{ccc}5& 7& 74\\ 8& 4& 80\\ 6& 9& ....\end{array}$

Answer 1

The third number of each row is the sum of the squares of the first and second numbers.
$a^2+b^2=c$
$5^2+7^2=25+49=74$
$8^2+4^2=64+16=80$
$6^2+9^2=36+81=117$