if q^2-1 is divisible by 8 if q is _____

Answer:
if q is odd
Step-by-step explanation:
Hello,
Either q is odd or is even.
Case 1 - we can find k integer so that q = 2k
Then, in the case
[tex]q^2-1=4k^2-1[/tex]
This is not divisible by 8, for instance, q = 6
[tex]q^2-1=36-1=35=7*5[/tex]
Case 2 - we can find k integer so that q = 2k+1
[tex]q^2-1=(2k+1)^2-1=4k^2+4k+1-1=4k(k+1)[/tex]
k(k+1) is divisible by 2 so the initial number is divisible by 8
Conclusion, the answer is q is odd.
Thanks