Question

prove that if x and y are both posetive odd integer then x square +y square is even but not divisible by 4​

Answer 1

Answer:

for any odd number x

x^2 = odd

for any two odd numbers a and b

a + b = 2c where z is odd

let a = x^2 and b = y^2

so x^2 + y^2 = a + b = 2c

so even but not divisible by 4