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Extremely hard maths question

f(x) = ex e^x

Show that

f(|x|) can be equally written as a quadratic equation in the form 1+ax2+bx 1+ax^2+bx where a & b are to be determined.
Reply 1
Avatar for TeeEm
TeeEm
19
Original post by AK 12
f(x) = ex e^x

Show that

f(|x|) can be equally written as a quadratic equation in the form 1+ax2+bx 1+ax^2+bx where a & b are to be determined.


what was that again?
Reply 2
Avatar for Zacken
Zacken
22
Original post by AK 12
f(x) = ex e^x

Show that

f(|x|) can be equally written as a quadratic equation in the form 1+ax2+bx 1+ax^2+bx where a & b are to be determined.


Are you saying that e∣x∣=1=bx+ax2\displaystyle e^{|x|} = 1 = bx + ax^2 for some constant a,b∈Ra,b \in \mathbb{R}? :rofl:
Reply 3
Avatar for Zacken
Zacken
22
Original post by AK 12
f(x) = ex e^x

Show that

f(|x|) can be equally written as a quadratic equation in the form 1+ax2+bx 1+ax^2+bx where a & b are to be determined.


exp⁡(∣x∣)=∑k=0∞∣x∣kk!\displaystyle \exp(|x|) = \sum_{k=0}^{\infty} \frac{|x|^k}{k!}, so...
Reply 4
Avatar for Notnek
Notnek
21
Original post by AK 12
f(x) = ex e^x

Show that

f(|x|) can be equally written as a quadratic equation in the form 1+ax2+bx 1+ax^2+bx where a & b are to be determined.

a=−1x2\displaystyle a=\frac{-1}{x^2}

b=e∣x∣x\displaystyle b=\frac{e^{|x|}}{x}

Or not. Please post the question exactly as you see it.
(edited 8 years ago)
Reply 5
Avatar for Zacken
Zacken
22
Original post by notnek
a=−1x2\displaystyle a=\frac{-1}{x^2}

b=e∣x∣x\displaystyle b=\frac{e^{|x|}}{x}

Or not. Please post the question exactly as you see it.


I don't think that is correct, a quadratic equation is a polynomial of the form ax2+bx+cax^2 + bx + c with a,b,ca, b, c constant and a≠0a \neq 0.
Reply 6
Avatar for Notnek
Notnek
21
Original post by Zacken
I don't think that is correct, a quadratic equation is a polynomial of the form ax2+bx+cax^2 + bx + c with a,b,ca, b, c constant and a≠0a \neq 0.

A quadratic equation also contains an '='.

I think we can make up our own rules for this question :smile:
Reply 7
Avatar for Zacken
Zacken
22
Original post by notnek
A quadratic equation also contains an '='.

I think we can make up our own rules for this question :smile:


Fair enough, although he probably meant quadratic function. I think we can both agree that this post is a trainwreck... :smile:
Reply 8
Avatar for AK 12
AK 12
OP
7
Original post by notnek
a=−1x2\displaystyle a=\frac{-1}{x^2}

b=e∣x∣x\displaystyle b=\frac{e^{|x|}}{x}

Or not. Please post the question exactly as you see it.


Original post by Zacken
exp⁡(∣x∣)=∑k=0∞∣x∣kk!\displaystyle \exp(|x|) = \sum_{k=0}^{\infty} \frac{|x|^k}{k!}, so...


Original post by TeeEm
what was that again?


Original post by Zacken
Are you saying that e∣x∣=1=bx+ax2\displaystyle e^{|x|} = 1 = bx + ax^2 for some constant a,b∈Ra,b \in \mathbb{R}? :rofl:


It was a step question. I'm preparing for it and need help
Reply 9
Avatar for TeeEm
TeeEm
19
Original post by AK 12
It was a step question. I'm preparing for it and need help


Post a photo of the actual question please
Reply 10
Avatar for Notnek
Notnek
21
Original post by AK 12
It was a step question. I'm preparing for it and need help

Which paper/question?
Original post by AK 12
It was a step question. I'm preparing for it and need help


Can we please see the full question, or at the very least tell us which paper and question it is?
Reply 12
Avatar for AK 12
AK 12
OP
7
Original post by 16Characters....
Can we please see the full question, or at the very least tell us which paper and question it is?


Original post by notnek
Which paper/question?


Original post by TeeEm
Post a photo of the actual question please


It also says a & b can be transcendental
Reply 13
Avatar for Zacken
Zacken
22
Original post by AK 12
It also says a & b can be transcendental


0/10 troll.

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