#1
Hello people, I'm desperate. I've been gone from school for three weeks, and I have a Math test tomorrow. And I've forgotten stuff I need to know, so if someone could tell me how I solve these I'd be glad! I need the way you do it, not just the answers. I work with something called polynom in Swedish, and I have no ****ing clue what its called in English. Basically, there are four solutions for X in this case.

This is what I got: x^4-10x^2+9=0. x^2 is re-written t. So the number we have is:

x^4 - 10t + 9= 0

It has FOUR solutions:

x1:
x2:
x3:
x4:

How do I figure this out? Any help would be greatly appreciated!

I'll probably post more stuff here if I can get help.

-DW
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#2
If t = x^2, the new formula is t^2 -10t + 9 = 0. Then just solve the quadratic. And sub t = x^2 in again.
#3
Quote by chubbychunks
If t = x^2, the new formula is t^2 -10t + 9 = 0. Then just solve the quadratic. And sub t = x^2 in again.

+1

this is all you need to solve this problem, then, if you dont know nothing at all its serious ****, son, the pits not the right place. Get your maths book and revise all you can. Stay calm, never panic! those exercises are easy
#4
*throws up all over maths*
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#5
Quote by swinghead
+1

this is all you need to solve this problem, then, if you dont know nothing at all its serious ****, son, the pits not the right place. Get your maths book and revise all you can. Stay calm, never panic! those exercises are easy


Ah, from there I can just use the formula-thingy. Ignore the numbers, I just drew somethign real quick. Please god let it be this one. It looks something like this:

Quote by Ichikurosaki
sloth is hacking away feebly at the grass because he is a sloth but he was trying so hard ;_; hes all "penguin im HERE i am here to help you penguin"
#6
Quote by chubbychunks
If t = x^2, the new formula is t^2 -10t + 9 = 0. Then just solve the quadratic. And sub t = x^2 in again.

This is correct. This equation factors to (t-9)(t-1)=0, which means t=9,1. Since t=x^2, x=3, -3, 1, -1.
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#7
Quote by KrgrHomebrew
This is correct. This equation factors to (t-9)(t-1)=0, which means t=9,1. Since t=x^2, x=3, -3, 1, -1.
...I think he just wanted a hint


Edit: Demon, revise the formula. It's x=(-b+-(sqrt:(b^2-2ac)))/(2a).


I think....lol.
Last edited by Wratheh at Feb 27, 2008,
#8
^^ its b^2 - 4ac in the quadratic formula
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#11
the bad thing about this is that after you do the quadratic formula your going to have to answer with polars.
#12
Quadramabatic Thingamabobbers.
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#13
Quote by samuwel
^^ its b^2 - 4ac in the quadratic formula

Ah, close though. But seriously, someone's already answered it lol.
#14
This is what I got: x^4-10x^2+9=0. x^2 is re-written t. So the number we have is:


t² - 10t + 9= 0

D = b² - 4AC = 100- 4*1*9 = 64 = 8²

t1 = (-b+D^(1/2))/2A = (10+8)/2 = 9
(X^(1/2) = square root of X)
t2 = (-b-D^(1/2))/2a = (10-8)/2 = 1

=> X1 = 9^(1/2) = 3
X2 = = -3
X3 = 1^(1/2) = 1
X4 = = -1

V=[-3, -1 ,1 ,3]

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#15
Why would you use the formula.
Just factorize it.
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#16
Quote by Ur all $h1t
Why would you use the formula.
Just factorize it.

It's cause I have a deep sensual passion for formulas.

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