Page 1 of 3

Math Help Forum

PostPosted: Mon Oct 29, 2007 2:48 am
by JustcallmeDrago
I see Ike is on here.

Hey Ike,

how would you factor x^4-(a^2)(x^2)+16a^4 ?

It looks like a simple binomial squared but the " -a2x2 " has me stumped. how can you possibly get this?

PostPosted: Mon Oct 29, 2007 3:01 am
by Ikerous
If you take u=x^2 and w=a^2 you get u^2 - wu + 16w^2

That doesn't seem factorable :/

I'll keep looking at it though

PostPosted: Mon Oct 29, 2007 3:06 am
by JustcallmeDrago
Ikerous wrote:If you take u=x^2 and w=a^2 you get u^2 - wu + 16w^2

That doesn't seem factorable :/

I'll keep looking at it though


There are others, but that is the most irritating one...

PostPosted: Mon Oct 29, 2007 3:09 am
by Ikerous
You can post them. I might fail less at those than this one.

PostPosted: Mon Oct 29, 2007 3:17 am
by JustcallmeDrago
Ikerous wrote:You can post them. I might fail less at those than this one.


=D yay!

x^8 + x^3

I got x^3(x^5 +1), but that just feels wrong.


Same with x4y2 + 2x3y2 + x2y2 - x2y4

I factored out x2y2 and got x2y2(x2 + 2x + 1 - y2), which is ugly :{

And I don't even know where to begin with x^(2a+1) + x^(a+1) - 6x

Answer/don't answer any you want (or don't want) to.

PostPosted: Mon Oct 29, 2007 3:22 am
by Ikerous
JustcallmeDrago wrote:
Ikerous wrote:You can post them. I might fail less at those than this one.


=D yay!

x^8 + x^3

I got x^3(x^5 +1), but that just feels wrong.


Same with x4y2 + 2x3y2 + x2y2 - x2y4

I factored out x2y2 and got x2y2(x2 + 2x + 1 - y2), which is ugly :{

And I don't even know where to begin with x^(2a+1) + x^(a+1) - 6x

Answer/don't answer any you want (or don't want) to.

I'd say that's as factored as the first one gets. The second one might be able to go a little farther with x^2 y^2 [(x+1)^2 - y^2]
Which would go to x^2 y^2 (x+1-y)(x+1+y)

As for the last one you can factor out an x^(a+1) and get x^(a+1) [x^a + 1] - 6x

PostPosted: Mon Oct 29, 2007 3:34 am
by JustcallmeDrago
for #3 I can't believe i didn't realize x^2a+1 is similar to a normal exponent.

as for #2, that really helped and i see a difference of squares in there. (well, i just saw you edited that in there... but yeah i did find that.

i feel i've done pretty good; i have done 75 of these so far.

how about -(x-y)^2 + c^2 ? nothing is obvious past simplifying... :/

PostPosted: Mon Oct 29, 2007 3:38 am
by Ikerous
JustcallmeDrago wrote:how about -(x-y)^2 + c^2 ? nothing is obvious past simplifying... :/

You can turn it around and get c^2 - (x-y)^2 which makes (c-x+y)(c+x-y)

PostPosted: Mon Oct 29, 2007 3:40 am
by JustcallmeDrago
Ikerous wrote:
JustcallmeDrago wrote:how about -(x-y)^2 + c^2 ? nothing is obvious past simplifying... :/

You can turn it around and get c^2 - (x-y)^2 which makes (c-x+y)(c+x-y)

Oh. :oops: :oops:

PostPosted: Mon Oct 29, 2007 4:10 am
by TSchultz
In[1]:= Factor[x^4 - (a^2) (x^2) + 16 a^4]
Out[1]= (4 a^2 - 3 a x + x^2) (4 a^2 + 3 a x + x^2)

PostPosted: Mon Oct 29, 2007 4:13 am
by JustcallmeDrago
TSchultz wrote:In[1]:= Factor[x^4 - (a^2) (x^2) + 16 a^4]
Out[1]= (4 a^2 - 3 a x + x^2) (4 a^2 + 3 a x + x^2)


so how did you get that?

PostPosted: Mon Oct 29, 2007 4:13 am
by TSchultz
Mathematica.

PostPosted: Mon Oct 29, 2007 4:18 am
by JustcallmeDrago
TSchultz wrote:Mathematica.


Is it free? or does it show you the steps?

PostPosted: Mon Oct 29, 2007 4:23 am
by TSchultz
For me it was free. It's free for all BU students, and all students at my high school have BU ID's so we can get it. But otherwise it costs a fair bit (100+ depending on if you're a student or not I think).
And sorry :/ doesn't show the steps. But there's an add on package that does I think.

PostPosted: Mon Oct 29, 2007 4:24 am
by JustcallmeDrago
TSchultz wrote:For me it was free. It's free for all BU students, and all students at my high school have BU ID's so we can get it. But otherwise it costs a fair bit (100+ depending on if you're a student or not I think).
And sorry :/ doesn't show the steps. But there's an add on package that does I think.


X|