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#1 Exercises » Require an explanation?? » 2014-02-11 08:02:02

Yusuke00
Replies: 2

Ok so i have the next exercise.





I didn't had any problems solving a) and b)
What about c?
Can anyone tell me how to resolve it?
I googled it and found out that's Si(x)(whatever that is) and i don't know about what's that since i'm just last grade of high school.
Any help?

#2 Re: Exercises » Question about polynomial ecuation » 2014-02-10 04:02:37

Indeed,good point you are right.

http://www.mathsisfun.com/data/function-grapher.php?func1=sqrt%28x%29&func2=2

#3 Re: Exercises » Question about polynomial ecuation » 2014-02-10 03:19:38

That would be quite hard.
I know the problem is to prove that x does not have roots on (-1,0) because it's easy to see on the other cases.Ideas?

#4 Re: Exercises » Question about polynomial ecuation » 2014-02-10 02:35:06

You got it wrong.
In my opinion the first one is always positive for any x real but i don't really know how to prove it.

#6 Re: Exercises » Question about polynomial ecuation » 2014-02-09 04:55:51

It's N* sorry math. I don't really know how to write N* or R*+.How you do that?

#7 Re: Exercises » Question about polynomial ecuation » 2014-02-09 04:52:09

Done yeah cool now i found out how it works. hehe

#8 Exercises » Question about polynomial ecuation » 2014-02-09 04:41:46

Yusuke00
Replies: 13

Hey guys.I have a little question or just a personal wonder about them.


Question is:
for any
?
What about 
?
Test:

#9 Re: Exercises » A nice integral » 2014-02-06 21:48:48

integral of 1/(sin^4x+cos^4x)dx

#10 Re: Exercises » A nice integral » 2014-02-06 20:53:51

f:[0,3]->R f(x)=max{3-x,2x+[x]} . Show that f is integrable on[0,3] and calculated integral of f(x)

#12 Re: Exercises » A nice integral » 2014-02-06 00:58:16

ok i understand....thank you!

#13 Exercises » A nice integral » 2014-02-05 22:59:23

Yusuke00
Replies: 16

integral of 1/(x^4+x^2+1):D:D

#14 Re: Exercises » Polynomial Ecuation » 2014-02-04 07:53:08

It means that f(x) =y,y is part of R.

#15 Re: Exercises » Polynomial Ecuation » 2014-02-04 05:48:53

But it's very helpful,i like it.Thank you very much ^_^.

#16 Re: Exercises » Polynomial Ecuation » 2014-02-04 05:19:46

For a>=1 there are real solutions.For a<1 there are not.That function grapher is for R not for C.

#17 Re: Exercises » Polynomial Ecuation » 2014-02-04 04:33:44

x1 are the solutions to the ecuation like...
f(x1)=0,f(x2)=0,f(x3)=0,f(x4)=0;
Sorry that's how i know to note them.

#18 Re: Exercises » Polynomial Ecuation » 2014-02-04 02:03:54

Yes i had the same ecuations,but i've been tired and just couldn't focus yesterday.Got them now thank you.

By the way,any clues on 1st problem?

#19 Re: Exercises » Polynomial Ecuation » 2014-02-03 19:03:36

Ok i got those ecuations either.W/E i'm stupid.Thank you.

#20 Re: Exercises » Polynomial Ecuation » 2014-02-03 09:57:39

bobbym wrote:

Hi;

f(1)=9
f(2)=-5
f(3)=0
f(4)=35

Could you describe your solution step by step please? For f(1)=8 not 9 sorry.

#21 Re: Exercises » Polynomial Ecuation » 2014-02-03 07:33:29

Ok guys a second problem

f(1)=8
f(2)=-5
f(3)=0
f(4)=35

f=?

The thing is i know how to solve the problem but i cannot really solve the system.
f(3)=0 -> x1=3 solution ->f = (X-3)(aX^2+bX+c)==>
==>f=aX^3+(b-3a)X^2+(c-3b)X-3c
so f(3)=0 ==>-3c=0 =>c=0

f(1)=8 ==> a+b=-4
f(2)=-5 ==>-4a-2b=-5==>4a+2b=5
f(4)=35 ==> 16a+4b=35

Can anyone solve the system or at least tell me where i'm wrong ? I'm getting very mad here.

#22 Re: Formulas » Solving cubic equations in general » 2014-02-02 20:23:38

Also you could use Viette's formulas and the fact that f=(X-x1)(X-x2)(X-x3) where x1,x2,x3 are roots of the ecuation.

#23 Exercises » Polynomial Ecuation » 2014-02-02 07:28:49

Yusuke00
Replies: 14

Hello guys long time no see,got a new exercise:

On R[X] f=X^4-aX^3-aX+1

Proove that if |a|<1 then |x1|=|x2|=|x3|=|x4|=1;
Good luck.

#24 Re: Exercises » Mathematical proofs? » 2013-11-25 05:47:23

How do you write mathematical here?
I mean with all the symbols and etc.

#25 Re: Exercises » Mathematical proofs? » 2013-11-25 02:08:10

Interesting proof,i thought of a different one.

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