Answer:
<u>Commutative property:</u> states that the order in which we multiply numbers does not change the product.
<u>Associative property:</u> states that you can add or multiply regardless of how the numbers are grouped (aka parenthesis).
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Answer:
Step-by-step explanation:
Hello, please consider the following.

So this is divisible by 3.
Now, to prove that this is divisible by 9 = 3*3 we need to prove that
is divisible by 3. We will prove it by induction.
Step 1 - for n = 1
4+17=21= 3*7 this is true
Step 2 - we assume this is true for k so
is divisible by 3
and we check what happens for k+1

is divisible by 3 and
is divisible by 3, by induction hypothesis
So, the sum is divisible by 3.
Step 3 - Conclusion
We just prove that
is divisible by 3 for all positive integers n.
Thanks