Question

proof that the squar of any positive integer is on the form 5m,5m+1, 5m+4​

Answer 1

consider m=-2

in eq 1

5m=5×(-2)^2=20

5m+1=5×(-2)^2+1=21

5m+4=5×(-2)^2+4=24

above we consider as m is negative integer must be positive.