Expand and Factorise Using Difference of Two Squares

What is ALWAYS the first step when factoring?

• Look for the GCF

• Write a, b, and c

• Difference of squares

• Use the X-Puzzle

Which of these can factor using difference of two squares?

• 144x² - 49y²

• x² + 4x - 12

• 100x² + 20x + 1

• 14x - 16

Which one is false about the difference of two squares?

• We can factor because there is addition sign.

• We can factor because there is a perfect squared number (Example: x², 25, 49)

• Formula: a² - b² = (a + b) (a - b)

• We can factor because there is minus sign.

We can't factor using difference of two square this

49x² + 4y². Why?

• Because 4 is not a perfect cubed number.

• Because 4 is not a perfect squared number.

• Because 49 is not a perfect squared number.

• Because we can't factor using difference of two squares if it is addition sign.

Factor 4x²-9

• (4x-9)(4x+9)

• (2x-3)(2x+3)

• 2x-3

• (2x-4.5)(2x+4.5)

Factor x²-25

• ( x + 5 ) ( x - 5 )

• ( x - 5 ) ( x - 5 )

• ( x + 5 ) ( x + 5 )

• Prime

Factor completely.

121x² - 49

• ( 11x - 7 ) ²

• ( 11x - 7 ) ( 11x - 7 )

• ( 11x + 7 ) ( 11x - 7 )

• ( 12x + 7 ) ( 12x - 7 )

Fully Factor the Following
25x²-81

• (5x-9)²
• (5x+9)(5x-9)
• 25(x-9)²
• (9x+5)(9x-5)

Factor completely.

49x² + 16

• ( 7x + 4 ) ( 7x - 4 )

• ( 7x + 4 ) ( 7x + 4 )

• ( 7x - 4 ) ²

• does not factor (SUM of squares)

32n² - 50
(Check for a GCF)

• (16n - 25)(16n + 25)
• 2(8n - 25)(8n + 25)
• 2(4n + 5)(4n - 5)
• Not Factorable