Alg2 help plz! test tommorow

[hollerback1]

How do you factor cubic polynomials?

x^3 - 125

27x^3 + 1

I don't know how to do these, please explain and help.

Thanks. :wink:

 

[skeeter]

x³ - 125 = x³ - 5³

use the factoring pattern ...

a³ - b³ = (a - b)(a² + ab + b²)

27x³ + 1 = (3x)³ + 1³

use the factoring pattern ...

a³ + b³ = (a + b)(a² - ab + b²)

 

[hollerback1]

um...can u tell me the answer?

How do i kno what a and b is?

 

[jolly]

Skeeter practically gave you the answer. Try it.

 

[stapel]

can u tell me the answer?

Just apply the formulas provided.

You need to learn how to recognize the patterns, so you can plug them into the formulas. (And you'll need to memorize those formulas, too.)

eliz.