Question

64b-9b^3
factor
awards will be given

Answer 1

Looking for help or an answer?

Answer 2

both

Answer 3

Okidoki. What do both 64b and 9b^3 have in common?

Answer 4

2?

Answer 5

Just a "b." You can pull a "b" out of 64b and out of 9b^3.

Answer 6

oh...ok.

Answer 7

Does that part make sense?

Answer 8

I can rephrase it if you want.

Answer 9

-55b^3

Answer 10

thats the answer

Answer 11

no that makes sense...I just thought i was finding a common

Answer 12

Ah, I see.

When we pull out a b from 64b, we are just left with the 64. When we pull it out of the 9b^3, we are left with 9b^2 (we reduce the power by 1)
\[64b-9b^3=b(64-9b^2)\]
If you distribute that b, you'll end up back where you started.

Answer 13

b(8+3b)(8-3b)

Answer 14

So ignore the b on the outside. You're just concerned with the stuff inside the parentheses. So you have to factor
\[64-9b^2\]

Answer 15

ok...

Answer 16

Where did I lose you?

Answer 17

I am confused at why we pull the b out. There are just so many types of problems and it's hard to remember what to do on each one.

Answer 18

Since b is only common between the two terms, we pulled it out, that's what the factorisation means

Answer 19

Ah, yes. This is a far more difficult problem than the rest of them. Basically, here's the idea:

We know what to do with something that has an x^2 term, an x term, and a constant term.
However, we don't know how to deal with anything that has an x^3 term, or an x^4 term, or an x^5 term, etc. Anything larger than an x^2 will need different tools.
So what we have is something with a b^3. We don't know how to deal with that. But if we can get rid of one of the b-terms by factoring it out, we can treat it like a b^2 term.
This problem probably isn't the best one to start playing with. It's difficult even if you know what you're doing.

Answer 20

thanks for that...it is ALL difficult. :O

Answer 21

Heh, would you like me to give you a couple and it might start to make sense? I don't want to give you extra stuff on top of your homework if you're under a time crunch, but you might understand it better for an exam or for future problems.

Answer 22

we can try. I am under a bit of a time crunch but not too bad. I just have to make sure I am able to get this assignment done.

Answer 23

Okay. Maybe this would be better then if you're under a time crunch:
http://www.khanacademy.org/video/solving-a-quadratic-by-factoring?playlist=Algebra

Answer 24

thank you

Answer 25

Sure thing. Let me know if you want some examples. I don't mind walking you through them.