Factor completely: 3bx^2 − 9x^3 − b + 3x

Question

anonymous · Answer

$$3bx ^{2}-9x ^{3}-b+3x$$

anonymous · Answer

This is Factoring by Grouping btw and every time I attempt it I get:
$$3x ^{2}(b-3x) and -1(b+3x)$$

anonymous · Answer

Possible answers:

(b − 3x)(3x^2 − 1) 

 (b + 3x)(3x^2 + 1) 

 (b + 3x)(3x^2 − 1) 

 Prime

anonymous · Answer

(3 x^2-1) (b-3 x)

anonymous · Answer

Can you tell me how you got it :)

luigi0210 · Answer

You messed up on your factoring by grouping

anonymous · Answer

Did I put the negative and positive signs wrong?

luigi0210 · Answer

You see how you took out the -1 from the b? You forgot to take out a -1 from the +3b, making it -3b

anonymous · Answer

is it because of the -9x^3?

anonymous · Answer

Don't group them together, like what Luigi said...

luigi0210 · Answer

No, grouping method works, you just made a common mistake

anonymous · Answer

So the 3x^2 was affected by the -9x^3

anonymous · Answer

3bx^2 − 9x^3 − b + 3x

3bx^2-9x^3-b+3x
rearranging the terms 3bx^2-b-9x^3+3x
b(3x^2-1)-3x(3x^2-1)
(b-3x)(3x^2-1)


Sorry, I don't know how to use the equation tool :P