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ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
As they always say: find \(f'(x)\) and equate that to \(0\).
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
@chochko What would \(f'(x)\) be here?
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
4x^3+12x^2
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
Well that's correct  now equate it to zero.
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
Solve this equation:\[\rm 4x^3 + 12x^2 = 0\]
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
4x^3+12x^2=0
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
Yeah, I meant 4x^3 + 12x^2 = 0
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
sry my computer is really slow. Would you factor out a 4?
 2 years ago

Yahoo! Group TitleBest ResponseYou've already chosen the best response.1
Yu.. 4x^2 ( x3) = 0 4x^2 = 0 x = 0 x3 = 0 x = 3
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
Mine too, and you can factor 4x^2 out.
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
Yep, and what Yahoo! said are the critical points. ;)
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
thank you but im not done . that is just one part..can you help yahoo or ParthKohli?
 2 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.1
the next part is to differentiate it again :P to determine its nature
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
You guys must be in the same school.
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
using the second derivitive test which is 12x^2+24x=0 set to 0 to determine all relative extrema, indicating the x and Y values and wheteher is a max or a min. Help please
 2 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.1
lol @ParthKohli: the next step is common sense. @chochko: with the differentiataed function sub the \(x\) that you found in the first step if its a negative then its concave down => max. if its concave up then => min
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
Sorry, was on another question, and yeah  that's the way I was taught too.
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
so in 12x^2+24x Sub the x for the critical numbers and the result is the relative extrema? is that the Max and Min as well?
 2 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.1
max or min concave up => min concave down => max
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
so which part is the relative extrema? i really suck at math btw?
 2 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.1
well i googled; relative extrema and max/ min extrema is the same thing
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
f''(0)=0 min f''(3)=36 Max Is this correct?
 2 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.1
i dont know; i dont have a calculator with me but if its you have to check if it has a horizontal point of inflexion
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
Ok, so the intervals are the critical points right? where are they increasing and decreasing?
 2 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.1
critical points are the stationary points on the curve since \(f(x)=0\) you differentiate it twice to determine if its increasing or decreasing increasing \(f''(x) >0\)
 2 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.1
i think i made a mistake; increasing \(f'(x)>0\)
 2 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.1
when the function is decreasing \(f'(x)<0\)
 2 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.1
i mean you differetiate it once; to see if its increasing or decreasing sorry; im sick
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
so using the f'(x)=0 and plug in 0 and 3 for x to find where f(x) is increasing or decreasing?
 2 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.1
oh no no im getting tired @ParthKohli: may like to explain :)
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
ok thanks a lot
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
@ParthKohli are you able to help me finish this one
 2 years ago

Mimi_x3 Group TitleBest ResponseYou've already chosen the best response.1
I think I should explain; since Parth is hiding :P \(f'(x) = 0\) you are finding the \(x\) values that is the STATIONARY point. \(f'(x) >0\) is the \(x\) values were the function is INCREASING \(f'(x)<0\) is where the function is DECREASING. The second derivative is the deirivative of the derivative. The curve \(y=f(x)\) is concave up when \(f''(x)>0\) and concve down when \(f''(x)<0\)
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
Sry, back.
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
Didn't notice the tag right there. :P
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
Increasing on ( inf, 0) (0,3) then decreasing (3, inf) idk if its correct?
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
Well your \(\rm f'(x)\) function is \(\rm 4x^2 +12x \) and the function is stationary at x = 3,0.
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
What is the question again?
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
State the intervas for which f(x) is increasing or decreasing So i tested the values 1, 1, 4 And got F'(1)=16 inc f'(2)=8 inc f'(4)=64 dec. idk if its correct?
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
That's right.
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
So it starts decreasing after 3.
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
(inf, 0) (0,3) increasing then (3, inf) decreasing Are the intervals right?
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
Let's test f'(5). f'(x) = 4x^2 + 12x f'(5) = 4(5)^2 + 12(5) = 4(25)  60 = 100  60 = 160
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
It's decreasing at f(5).
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
The best way is to ask Wolfram for the graph. :)
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
huh? whos that?
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
Enter your function and see its graph.
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
ok can you help me find the possible inflection points
 2 years ago

chochko Group TitleBest ResponseYou've already chosen the best response.0
@ParthKohli can you help just a lil bit left
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
Sorry, back.
 2 years ago

ParthKohli Group TitleBest ResponseYou've already chosen the best response.1
Damn... I've disabled the tag notifs.
 2 years ago
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