Induction - Divisibility Proof (Proving that 4^(n+1) + 5^(2n-1) is divisible by 21)

In this divisibility proof, I show you how to prove that 4^(n+1) + 5^(2n-1) is divisible by 21.

These types of questions (powers together with divisibility) are very common. The trick for the inductive step is knowing when to split the coefficient(s) into an addition of terms. I'll try posting another question of this kind to make it clearer.

Hope this helps :)

[arupjyotihui]

Thanks bro
Love from india🇮🇳
Your video help me much more