Bunuel wrote:
If x is a positive integer and x + 2 is divisible by 10, what is the remainder when x² + 4x + 9 is divided by 10?
A. 1
B. 3
C. 5
D. 7
E.9
Given: x + 2 is divisible by 10
In other words x + 2 is a multiple of 10, which means we can write: x + 2 =10k for some integer k
We want to know what the remainder will be when we divide x² + 4x + 9 by 10.
x² + 4x + 9 = x² + 4x +4 + 5
= (x +2)(x+2) + 5
=(10k)(10k) + 5
= 100k² + 5
So now we want to know what the remainder will be when we divide
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