Nature of the roots of the equations

In summary, Homework Statement asks about the zeros of one of the polynomials, and provides a summary of the content.
  • #1
shivam01anand
37
0

Homework Statement





Homework Equations




The given equations are;

Q.1) Find the no of + roots of the equation x^4 -4x+1=0

Q.2) Find the no. of negative roots of the eqn x^4-4x-1=0

Q.3) Find the no of complex roots of the eqn x^4-4x-1=0

The Attempt at a Solution

 
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  • #3
yes indeed but according to our maths teacher it's pretty rubbish in practical use because it just gives the MAXIMUM possible with any equation no matter the respective conditions..


no help i guess from that :(
 
  • #4
Have you learned about derivatives yet? This problem seems really well suited for a first and second derivative test and after a little argument you can answer the question.

I'm not sure if this is how your teacher wants it completed, I forget if derivatives are covered in pre-calculus, it's been awhile since I looked at a book.
 
  • #5
shivam01anand said:
yes indeed but according to our maths teacher it's pretty rubbish in practical use because it just gives the MAXIMUM possible with any equation no matter the respective conditions..


no help i guess from that :(

The Rule of Signs is but one tool in your previously empty toolbag.

You should know how many roots these equations will have. By careful use of this fact and the Rule of Signs, it may help you to narrow the numbers of each type of root.
 
  • #6
shivam01anand said:
yes indeed but according to our maths teacher it's pretty rubbish in practical use because it just gives the MAXIMUM possible with any equation no matter the respective conditions..
I think you'll find it has some value here. (And please clarify whether the three equations are supposed to be the same. As posted, they're not.)
 
  • #7
shivam01anand said:
...

The given equations are;

Q.1) Find the no of + roots of the equation x^4 -4x+1=0

Q.2) Find the no. of negative roots of the eqn x^4-4x-1=0

Q.3) Find the no of complex roots of the eqn x^4-4x-1=0

The Attempt at a Solution


shivam01anand said:
yes indeed but according to our maths teacher it's pretty rubbish in practical use because it just gives the MAXIMUM possible with any equation no matter the respective conditions..

no help i guess from that :(
Assuming that all three questions are regarding the same equation, then you are being asked about the zeros of one of the two following polynomials.

##\displaystyle P(x)= x^4 -4x+1 ##

OR

##\displaystyle Q(x)=x^4 -4x-1 ##

For either case, Descartes' Rule of Signs turns out to be very useful when combined with some other observations.

Maybe it's not rubbish for these polynomials.
 
  • #8
Yes i know a good deal on how to do the derivatives now after a year.

but these three separate questions were part of a question bank on the chapter QUADRATIC EQUATIONS.

So i guess calculus goes out of the window for now.

The only way to solve this is by discarte? and ofc derivative
 
  • #9
shivam01anand said:
Yes i know a good deal on how to do the derivatives now after a year.

but these three separate questions were part of a question bank on the chapter QUADRATIC EQUATIONS.

So i guess calculus goes out of the window for now.

The only way to solve this is by discarte? and ofc derivative
Well, you haven't resolved the question regarding which function (or equation) is being asked about.

If you're being asked about the roots of x4-4x-1 = 0 , then Descartes along with a nominal amount of knowledge about the zeros of polynomials, will give all the answers. While Descartes' Rule gives the maximum number of positive roots or maximum number of negative roots, if the number is fewer than either maximum, if the number of either is less than the maximum, then the amount that it is less is an even number. So for this equation there is one positive root and one negative root. How many roots does a degree 4 polynomial equation have?

...
 
  • #10
shivam01anand said:

Homework Statement





Homework Equations




The given equations are;

Q.1) Find the no of + roots of the equation x^4 -4x+1=0

Q.2) Find the no. of negative roots of the eqn x^4-4x-1=0

Q.3) Find the no of complex roots of the eqn x^4-4x-1=0

The Attempt at a Solution


Please check your PMs. It is against the rules of these forums to post a schoolwork question without showing any effort toward the solution. It is also against the PF rules for other posters to offer help when you show zero effort in your first post in a thread.
 

1. What is the "nature of the roots" in an equation?

The nature of the roots in an equation refers to the type of solutions that satisfy the equation. This can be determined by analyzing the discriminant (b²-4ac) of the equation, where a, b, and c are coefficients.

2. How can the nature of the roots be classified?

The nature of the roots can be classified into three categories: real and distinct, real and equal, and imaginary. Real and distinct roots occur when the discriminant is positive, real and equal roots occur when the discriminant is zero, and imaginary roots occur when the discriminant is negative.

3. What does it mean if an equation has real and distinct roots?

If an equation has real and distinct roots, it means that the equation has two different real number solutions. This can also be referred to as "two distinct solutions".

4. How do you determine the nature of the roots algebraically?

To determine the nature of the roots algebraically, you can use the quadratic formula: x = (-b ± √(b²-4ac)) / (2a). If the discriminant (b²-4ac) is positive, the equation will have two real and distinct roots. If the discriminant is zero, the equation will have one real and equal root. If the discriminant is negative, the equation will have two imaginary roots.

5. Can an equation have more than two roots?

Yes, an equation can have more than two roots. However, the quadratic formula will only give us two solutions. In cases where there are more than two roots, we would need to use other methods, such as factoring or graphing, to determine the additional solutions.

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