polymials factor

Question

 

25x²-16

Answer 1

this is the difference of two squares: √25x²=5x and √16=4

5x and 4: add them and subtract them and multiply the two binomials

(5x+4)(5x-4)

Answer 2

25x² - 16 can be expanded to (ax + b)(ax - b).  

You can notice this because the polynomial is subtraction (ax² - b) instead of addition (ax² + b)

and there is no middle term (such as the b in ax² + bx + c).

 

(5x + 4)(5x - 4)

= 25x² - 20x + 20x - 16

= 25x² - 16