Steps to Factor with Difference of Squares

• Check to make sure you have a difference of squares! You should have two perfect squares separated by a subtraction sign.

• Take the square root of each term.

• Write your two factors using the rule: a²-b² = (a+b)(a-b).

Factor 121 - 4b²

Remember: a² - b² = ​(a + b)(a - b)

There terms (121​) and (4b²) are both perfect squares.

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1) The √​121 = 11

2) The √4 = 2 and √b² = b so √(4b²) = 2b

Put that all together to see​

121 - b² = (11+ 2b) (11- 2b)​

Factor 16h² - 9a²

Remember: a² - b² = ​(a + b)(a - b)

There terms (16h²​) and (9a²) are both perfect squares.

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Therefore 16h² = (4h)² because the √​16=4 and √h² = h

AND 9a² = (3a)² because √​9=3 and √a²=a

SO​

We can ​factor 16h² - 9a² to (4h + 3a)(4h-3a)

Note: Check my work​

Factor Difference of Squares

You will hear me say difference of two perfect squares a lot (just how I learned it)

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BUT the general formula is

a² - b² = ​(a + b)(a - b)

NOTES

1) Notice that it is SUBTRACTION - it only works with subtraction

2) a² and b² will be perfect squares​

-Example a² could = 16x² and b²=81 so follow the pattern.

-16x² - 81 = (4x + 9)(​4x - 9) Check my work and make sure I am right.

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