Question

How do I factor a^4-4a^3-2a^2+12a+9

Answer 1

it looks binomial in structure

Answer 2

Okay...

Answer 3

but thats not always the case

Answer 4

start with the rational root thrm

Answer 5

if that doesnt get us someplace, then it gets messy

Answer 6

I've been trying to pair things up and then take out common factors but it's not working

Answer 7

factors of last term
+- ----------------
factors of first term

this would give us a pool of options to narrow down

Answer 8

1,3,9,-1,-3,-9

try using these as roots to divide out

Answer 9

or ... if f(1,3,9,-1,-3,-9) produces a zero, its a root

Answer 10

a^4 - 4a^3 - 2a^2 + 12a + 9
1 | 1 | 0

2 or 0 positive roots



a^4 + 4a^3 - 2a^2 - 12a + 9
1 | 1 | 0

2 or 0 negative roots

Answer 11

It's all gravy I figured it out , thanks

Answer 12

cool :)