Checking my answers
if f(x)=x^3-9x^2+15x+3
What is the relative maxima ?

- hba

Checking my answers
if f(x)=x^3-9x^2+15x+3
What is the relative maxima ?

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- chestercat

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- hba

I got 10.

- anonymous

Really??

- hba

Yeah really.

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## More answers

- anonymous

It will be right as it is calculated by the Great @hba
ha ha ha..

- hba

Thanks.

- hba

I have more question to get checked can i ask here or in a new post.

- anonymous

I don't know how to solve these types of questions..
Can you teach me how to solve it..??

- hba

@waterineyes
Ha Ha Ha Nice joke,first let me ask my questions.

- anonymous

First, we will take derivative..
Right??

- hba

Yeah.

- anonymous

So wait, I am doing it..

- hba

okay :(

- anonymous

f'(x) = 3x^2 - 18x + 15

- sirm3d

there are two extrema, 1 relative maximum and 1 relative minimum.

- anonymous

Should I factorize it??

- hba

put f'(x)=0

- anonymous

Yes I mean the same..

- hba

Then the answer is yes

- anonymous

\[x^2 - 6x + 5 = 0 \implies (x - 5)(x - 1) = 0\]

- anonymous

x = 5 and x = 1

- hba

Yes you are right

- hba

Now put 1 in the orignal equation.

- anonymous

Why not 5 ??

- hba

Because we are finding the relative maxima

- anonymous

f(1) = 10

- sirm3d

oooh, i misread the problem. relative maxima.

- hba

Correct.

- anonymous

So, we have to put smaller value??

- hba

Yes.

- anonymous

Just checking your answer..
Ha ha ha..

- anonymous

Now don't say, to find relative minima, we will put 5..

- hba

|dw:1355817149046:dw|

- hba

@waterineyes Check these two questions.

- anonymous

How to solve these now??

- hba

I got f'(x)=e in both the cases.

- hba

And f''(x)=1/e
for 1st
and
f''(x)=e
in the 2nd one.

- hba

So i am right ?

- anonymous

Are you sure it is e ??

- hba

Pretty sure
Because i did this one like 100 times when i was in High school

- anonymous

You have used division rule here??

- hba

U/V form.

- anonymous

For first :
\[f'(x) = \frac{1 - \ln(x)}{x^2}\]

- hba

Wait lemme check.

- anonymous

Take your time..

- hba

Yeah right

- hba

@waterineyes ?

- anonymous

Who is right??

- hba

The most intelligent @waterineyes

- anonymous

Not intelligent as you @hba

- anonymous

Now, find the second derivative..

- hba

Ha Ha Ha
Yeah wait.

- hba

I am getting something,which looks extremly wrong :/

- hba

@waterineyes
Here you go
\[f''(x)=-x-2x+2lnx/x^4\]
I kow it's wrong :/

- anonymous

Sorry busy helping other person..

- anonymous

Now I think, if it was e then it will be simpler..

- anonymous

Wait, let me check..

- hba

ok

- anonymous

You can add first two terms in the numerator..

- hba

Yeah i can add them so,
\[f''(x)=-3x+2lnx/x^2\]

- hba

@waterineyes So ?

- hba

@waterineyes
Ansoo kahan ho tum ?

- hba

@waterineyes
Answer tau sahi hai mera,Is ki working mushkil hai :/

- anonymous

Now what to do next??

- anonymous

I had a guest in home so busy there..
Sorry, let us now work together..

- anonymous

There??

- hba

yeah

- hba

@waterineyes Where should i continue ?

- anonymous

What we will do next after finding second derivative??
To find extreme value..

- hba

put it equal to 0

- anonymous

\[2 \ln(x) = 3x\]

- anonymous

Where are we going??
Is that right??

- hba

i think we should skip these lol,I am pretty sure about my answers :)
Do you know what is a stationary point ?

- anonymous

The point which is stationary is called Stationary Point, that's it..!!!

- hba

So,
if f(x)=ln(1+x^2)
What will be the stationary point ?

- anonymous

I think I should go now..
Ha ha ha..
Seriously, don't know..

- hba

Gurpreet :/
Chalo Bye.

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