Got Homework?
Connect with other students for help. It's a free community.
Here's the question you clicked on:
 0 viewing
guys help me find the concavity of f(x)= x^44x^3+4x^2. i kow the procedure but have problems with calculations. so helpp
 2 years ago
 2 years ago
guys help me find the concavity of f(x)= x^44x^3+4x^2. i kow the procedure but have problems with calculations. so helpp
 2 years ago
 2 years ago

This Question is Closed

acrossBest ResponseYou've already chosen the best response.0
Differentiate this function twice.
 2 years ago

ash2326Best ResponseYou've already chosen the best response.2
f(x)=x^44x^3+4x^2 f'(x)=4x^312x^2+8x f''(x)=12x^224x+8 let's find the inflection points where the curve changes concavity f''(x)=0 x=1+ 1/root 3 and 11/root 3 so x =0.42 and 1.577 here the curve changes concavity if f''(x)>=0 then f(x) is concave up if f''(x)<=0 then f(x) is concave down for the interval (infinity, 0.42] and [1.577, infinity) f(x)''>=0 for the interval[0.42,1.577] f''(x)<=0 so f(x) has concavity up in the interval(infinity, 0.42] and [1.577, infinity) and concavity down in [0.42, 1.577]
 2 years ago

suju101Best ResponseYou've already chosen the best response.0
is it correct to get intervals in decimal??
 2 years ago

ash2326Best ResponseYou've already chosen the best response.2
yeah, you can also write in radical like 1+1/root 3
 2 years ago

suju101Best ResponseYou've already chosen the best response.0
plz help me with this f(x)=x^3/(3x^2+1). for the same thing. i messed up while solving.
 2 years ago

PROSSBest ResponseYou've already chosen the best response.0
dw:1325942133129:dw First step find the first derivative
 2 years ago

PROSSBest ResponseYou've already chosen the best response.0
dw:1325942270219:dw simplify more
 2 years ago

PROSSBest ResponseYou've already chosen the best response.0
Now take the derivative again....
 2 years ago

PROSSBest ResponseYou've already chosen the best response.0
set = to 0 and solve to determine possible points of inflection...then choose values to the left and right of these zeros to determine if x>0 concave up or if x<0 concave down....
 2 years ago
See more questions >>>
Your question is ready. Sign up for free to start getting answers.
spraguer
(Moderator)
5
→ View Detailed Profile
is replying to Can someone tell me what button the professor is hitting...
23
 Teamwork 19 Teammate
 Problem Solving 19 Hero
 Engagement 19 Mad Hatter
 You have blocked this person.
 ✔ You're a fan Checking fan status...
Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.