Math Is Fun Forum

mathxyz

Member

From: Brooklyn, NY

Registered: 2024-02-24

Posts: 1,053

Analyze f(x)

Graph the given function over the indicated interval and approximate any local maximum and local minimum values. Determine where the function is increasing and decreasing. Round your answer to two decimal places.  DO NOT USE CALCULUS.

f(x) = -0.4x^4 - 0.5x^3 + 0.8x^2 - 2 on the interval (-3, 2)

Last edited by mathxyz (2024-03-24 09:59:08)

Bob

Administrator

Registered: 2010-06-20

Posts: 10,626

Re: Analyze f(x)

Calculate y for x = -3, -2, -1, 0, 1,  2 and plot the points. 

I used the function grapher and there are max and min values but oddly not in that domain.

Spotted the problem.  I copied your function as typed.  I think there's a decimal point  missing here 0.8x^2

Now the graph has max and min in the given domain.

Bob

---

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei
Sometimes I deliberately make mistakes, just to test you!  …………….Bob

mathxyz

Member

From: Brooklyn, NY

Registered: 2024-02-24

Posts: 1,053

Re: Analyze f(x)

Calculate y for x = -3, -2, -1, 0, 1,  2 and plot the points. 

I used the function grapher and there are max and min values but oddly not in that domain.

Spotted the problem.  I copied your function as typed.  I think there's a decimal point  missing here 0.8x^2

Now the graph has max and min in the given domain.

Bob

Yes, I edited my post. The coefficient of x^2 is 0.8.

Can you post the graph for me?

amnkb

Member

Registered: 2023-09-19

Posts: 253

Re: Analyze f(x)

Can you post the graph for me?

YOu can do the graph yourself in your phone
Go to Google Play Store
In 'search' box enter 'Graphing calculator plus 84 83'
Install app to get TI-84 emulator on your phone
TI-84 can do things like find the minimum on a graph
(and there's lots of tutorials, how-to's, etc online for Texas Instruments TI-84)

mathxyz

Member

From: Brooklyn, NY

Registered: 2024-02-24

Posts: 1,053

Re: Analyze f(x)

Can you post the graph for me?

YOu can do the graph yourself in your phone
Go to Google Play Store
In 'search' box enter 'Graphing calculator plus 84 83'
Install app to get TI-84 emulator on your phone
TI-84 can do things like find the minimum on a graph
(and there's lots of tutorials, how-to's, etc online for Texas Instruments TI-84)

Of course I can graph the function using many different apps.
My problem is uploading the graph image here.