Factoring a difference of two squares

Select the expression that is equivalent to m² - 25.
A.)  (m² - 10m + 25)
B.)  (m² + 10m + 25)
C.)  (m - 5)(m + 5)
D.)  (m - 5)²

m² - 25 is a difference of two squares.  That is, two perfect squares with a minus sign between them.

It is in the form of a² - b².  It factors into the form (a + b)(a - b).

m² - 25
= (m + 5)(m - 5)

The first term of the two binomials, is the square root of the first term of the difference of two squares.
The second term of the two binomials, is the square root of the second term of the difference of two squares.

Multiplication is commutative, meaning it can be switched around, without changing the result, to be:
C.)  (m - 5)(m + 5)

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