• Congratulations to the Class of 2024 on your results!
    Let us know how you went here
    Got a question about your uni preferences? Ask us here

polynomials (1 Viewer)

enigma_1

~~~~ Miss Cricket ~~~~
Joined
Feb 27, 2013
Messages
4,281
Location
Lords
Gender
Female
HSC
2014
Find the turning points of the polynomial 4x^3 − x^4 − 1 and hence state how many zeroes
they have.


How do you find how many zeroes they have?
Answer: 2 zeroes
 

QZP

Well-Known Member
Joined
Oct 7, 2013
Messages
839
Gender
Undisclosed
HSC
2014
I believe the question is asking for the zeroes of the gradient function, otherwise the 'hence' part is throwing me off :S
 
Last edited:

HeroicPandas

Heroic!
Joined
Mar 8, 2012
Messages
1,547
Gender
Male
HSC
2013
So find the stationary points of the polynomial and their nature, then draw up a quick inaccurate graph and there should be 2 x-intercepts
 

enigma_1

~~~~ Miss Cricket ~~~~
Joined
Feb 27, 2013
Messages
4,281
Location
Lords
Gender
Female
HSC
2014
nah, I'm pretty sure it aint. Cause for this example, 3x^4 − 4x^3 + 2,

The answer is zero...wtff
 

HeroicPandas

Heroic!
Joined
Mar 8, 2012
Messages
1,547
Gender
Male
HSC
2013
Heroic pandas! How do I draw it..
let polynomial be y

I got (0,-1) being a point of inflection and (3,26) being a maximum

As x--> -infinity, y --> - infinity
As x--> infinity, y--> -infinty

It looks like a mountain
 

QZP

Well-Known Member
Joined
Oct 7, 2013
Messages
839
Gender
Undisclosed
HSC
2014
Heroic pandas! How do I draw it..
There is a turning point at x = 3. Find F(3) and the value on the immediate left/right to establish the concavity at that point. Then you should be able to determine how many zeroes there are :) It's just translating the information from the graph of your gradient function (though there are many other ways to conceptualise it). HeroicPandas is right.
 

hit patel

New Member
Joined
Mar 14, 2012
Messages
568
Gender
Male
HSC
2014
Uni Grad
2018
It is possibly asking you for double roots or asking you to find the concavity at the point by y'' and y' and therefore drawing a sketch to obtain possible number of roots. Believe it or not but that is 4U maths from somwhere in the second / first exercise hyperbole :).
 

enigma_1

~~~~ Miss Cricket ~~~~
Joined
Feb 27, 2013
Messages
4,281
Location
Lords
Gender
Female
HSC
2014
Ohh, thanks hit, Heroic pandas, QZP! :)

Ahaha really? Well that justifies my freak out lol!
 

Vision

New Member
Joined
Oct 27, 2013
Messages
17
Gender
Male
HSC
2012
Ohh, thanks hit, Heroic pandas, QZP! :)

Ahaha really? Well that justifies my freak out lol!
Sorry to say, but sketching the graph isn't 4u, you should be learning it in 3u. You'll probably learn it soon though.
 

hit patel

New Member
Joined
Mar 14, 2012
Messages
568
Gender
Male
HSC
2014
Uni Grad
2018
Sorry to say, but sketching the graph isn't 4u, you should be learning it in 3u. You'll probably learn it soon though.
Terry lee 4 U Text Book Exercise 3.1 Q5).
 

Carrotsticks

Retired
Joined
Jun 29, 2009
Messages
9,494
Gender
Undisclosed
HSC
N/A
It is possibly asking you for double roots or asking you to find the concavity at the point by y'' and y' and therefore drawing a sketch to obtain possible number of roots. Believe it or not but that is 4U maths from somwhere in the second / first exercise hyperbole :).
The curve is a polynomial, and sketching polynomials (even with the aid of calculus) is in 3U.

Hell, even basic polynomial sketching is in 2U, but they are not identified as polynomials.
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top