a=9
a^2+40^2=41^2
a^2=41^2-40^2
if x^2-y^2, (x-y) (x+y) [that is formula]
so, a^2= (41-40) (41+40)
a^2= 1×81
a^2=81
a^2=9^2 (9×9=81)
^2 and ^2 are the same, so
9.4m questions
12.2m answers