1. ## Factoring

Factor
To go about the first one please show me the steps. Thanks
1. $(x+5)^4(x-9)^3+(x+5)^4(x-9)^4$
$(x+5)^4(x-9)^3[(1)+(x-9)]$?

2. $x^4-15x+144$
Prime?

2. ## Re: Factoring

Originally Posted by theloser
Factor
To go about the first one please show me the steps. Thanks
1. $(x+5)^4(x-9)^3+(x+5)^4(x-9)^4$
$(x+5)^4(x-9)^3[(1)+(x-9)]$?

This is correct so far, to finish

$(x+5)^4(x-9)^3[(1)+(x-9)]$

$(x+5)^4(x-9)^3(x-8)]$

Originally Posted by theloser
2. $x^4-15x+144$
Prime?
This one looks tricky, are you sure its not $x^4-15x^2+144$ ??

3. ## Re: Factoring

Originally Posted by pickslides
This is correct so far, to finish

$(x+5)^4(x-9)^3[(1)+(x-9)]$

$(x+5)^4(x-9)^3(x-8)]$

This one looks tricky, are you sure its not $x^4-15x^2+144$ ??
It is $x^4-15x^2+144$
its not a perfect squared and I don't see any factors of 144 that would total -15.

4. ## Re: Factoring

2. $x^4-15x+144$
Prime?
[/QUOTE]

$x^4>15x-144$ for all x in R ===> no factorization over R.

5. ## Re: Factoring

Originally Posted by theloser
It is $x^4-15x^2+144$
its not a perfect squared and I don't see any factors of 144 that would total -15.
Substitute:

x^2=t

6. ## Re: Factoring

I think its prime.

7. ## Re: Factoring

See the graph.

Not that you needed confirmation, but the discriminant (once you've made Zach's substitution) would have told you at a glance.