Question

Fill in the blank

$\begin{array}{ccc}7& 5& \left(36\right)\\ 9& 1& \left(25\right)\\ 12& 4& (-)\end{array}$

Answer 1

The third number in each row is the square of half of the sum of the first and second numbers.
Formula : ${\left(\frac{a+b}{2}\right)}^2=c$
$7+5=12;12÷2=6$; $6^2=36$
$9+1=10;10÷2=5$; $5^2=25$
$12+4=16;16÷2=8$; $8^2=64$