Question

if x and y are both odd positive integer then show that x square + y square is even not divisible by 4

Answer 1

Let x = 3 and y = 5
So x square = 3 squared = 9
And y square = 5 squared = 25
So, sum = 34
Hence we see how the sum is even BUT not divisible by 4
Let us take one more example,
x= 5
y = 7
5 square = 25
7 square = 49
Sum = 74
Which is even BUT not divisible by 4
Hence, Proved