Question

Factor 16x^4 – b^4 + 10b^2 – 25 completely.

A. (4x^2 + b^2)(2x + b)(2x – b) + 5(2b^2 – 5)

B. (4x^2 – b^2 – 5)(4x^2 + b^2 – 5)

C. (2x – b^2 + 5)(2x + b^2 – 5)(4x^2 + b^2 – 5)

D. (4x^2 – b^2 + 5)(4x^2 + b^2 – 5)

How do I get started?

Answer 1

I solved this problem by working in reverse. I started with choice A. (4x^2 + b^2)(2x + b)(2x – b) + 5(2b^2 – 5) and I successfully factored it into (16x^4 – b^4 + 10b^2 – 25). I'll check the others also. Tell me if you need step by step instructions.

Answer 2

I got the same result for A and D. I'm checking which one is the correct one. :)

Answer 3

@Blank  Ok I'll solve A and D and see what I get. Thanks

Answer 4

The thing is that A and D get the same result which is "16x^4 – b^4 + 10b^2 – 25 "

Answer 5

I'm suspecting that D is more complete.

Answer 6

Yep, this confirmed it: http://openstudy.com/study#/updates/514f2e6ce4b0d02faf5b2849
D. (4x^2 – b^2 – 5)(4x^2 + b^2 – 5)

Answer 7

@Blank I agree! A had slightly different like-terms. Thanks for your help.

Answer 8

ǝɯoɔlǝʍ ǝɹ,noʎ :)

Answer 9

@Blank  Oh but @RH 's answer is B.

Answer 10

For B, I get "16x^(4)-40x^(2)-b^(4)+25"

Answer 11

For D. (4x^2 – b^2 + 5)(4x^2 + b^2 – 5), I get "16x^4 – b^4 + 10b^2 – 25".
I still think it is D. Sorry about my mistake up top for mixing up B and D. :)

Answer 12

Yup. Got the same answer for B

Answer 13

No problem. I'm just really glad I'm getting help. Thanks again for putting up with me. :)

Answer 14

It's definitely D. It's exact.