sum of cubes

[Guest]

Here is the question that is confusing me:
8+ t^3

factor the sum of cubes:
This is what i have done:

a^3 + b^3 = (a + b) (a^2 -ab + b^2)

t^3 + (2)^3

my book says the answer is
(2 + t) (4-2t + t^2)

Could someone explain how that became the answer besides what I did?
Thanks so much.

 

[tkhunny]

Here is the question that is confusing me:
8+ t^3
(2 + t) (4-2t + t^2)

8 = 2³
2² = 4
-2*t

??? Where are you struggling? It looks like you should just be able to plug it in. Number first and variable last, maybe. 8 + t^3 = t^3 + 8 Do it the other way if it makes more sense.

 

[Guest]

thanks

I just struggle because I am a mom of 3 and work full time. My time for trying to learn all this is little. I am trying to learn to help my 15 year old when he has questions, so I don't look so dumb!

 

[tkhunny]

So, are you still stuck on this one or did that help? Seeing the form is the tricky part.

Something³ + (Something Else)³