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Difference of squares
A difference of square is when you start and end with a square but have no middle term. The middle term cancels out.
Example
16x^2 - 25
Factor
(4x - 5) (4x + 5)
Both terms are squared but, there's no middle term so it's a difference of squares.
When you expand it one bracket would be a positive the other would be a negative
In this expression both terms are squared
4^2
5^2
Now you factor it. You could see that in one bracket you subtract and the other you add. This is what a difference of square looks like.
(4x - 5) (4x + 5)
(4x - 5) (4x + 5)
16x^2 + 20x - 20x - 25
16x^2 - 25
Check
Expand
Simplify. The -20 and 20 cancels out
You get the same answer as before
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