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Using the intermediate value theorem

Show that the function f ( x ) = x 3 5 x 2 + 3 x + 6 has at least two real zeros between x = 1 and x = 4.

As a start, evaluate f ( x ) at the integer values x = 1 , 2 , 3 , and 4. See [link] .

x 1 2 3 4
f ( x ) 5 0 –3 2

We see that one zero occurs at x = 2. Also, since f ( 3 ) is negative and f ( 4 ) is positive, by the Intermediate Value Theorem, there must be at least one real zero between 3 and 4.

We have shown that there are at least two real zeros between x = 1 and x = 4.

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Show that the function f ( x ) = 7 x 5 9 x 4 x 2 has at least one real zero between x = 1 and x = 2.

Because f is a polynomial function and since f ( 1 ) is negative and f ( 2 ) is positive, there is at least one real zero between x = 1 and x = 2.

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Writing formulas for polynomial functions

Now that we know how to find zeros of polynomial functions, we can use them to write formulas based on graphs. Because a polynomial function    written in factored form will have an x -intercept where each factor is equal to zero, we can form a function that will pass through a set of x -intercepts by introducing a corresponding set of factors.

Factored form of polynomials

If a polynomial of lowest degree p has horizontal intercepts at x = x 1 , x 2 , , x n , then the polynomial can be written in the factored form: f ( x ) = a ( x x 1 ) p 1 ( x x 2 ) p 2 ( x x n ) p n where the powers p i on each factor can be determined by the behavior of the graph at the corresponding intercept, and the stretch factor a can be determined given a value of the function other than the x -intercept.

Given a graph of a polynomial function, write a formula for the function.

  1. Identify the x -intercepts of the graph to find the factors of the polynomial.
  2. Examine the behavior of the graph at the x -intercepts to determine the multiplicity of each factor.
  3. Find the polynomial of least degree containing all the factors found in the previous step.
  4. Use any other point on the graph (the y -intercept may be easiest) to determine the stretch factor.

Writing a formula for a polynomial function from the graph

Write a formula for the polynomial function shown in [link] .

Graph of a positive even-degree polynomial with zeros at x=-3, 2, 5 and y=-2.

This graph has three x -intercepts: x = −3 , 2 , and 5. The y -intercept is located at ( 0 , 2 ) . At x = −3 and x = 5 , the graph passes through the axis linearly, suggesting the corresponding factors of the polynomial will be linear. At x = 2 , the graph bounces at the intercept, suggesting the corresponding factor of the polynomial will be second degree (quadratic). Together, this gives us

f ( x ) = a ( x + 3 ) ( x 2 ) 2 ( x 5 )

To determine the stretch factor, we utilize another point on the graph. We will use the y - intercept ( 0 , 2 ) , to solve for a .

f ( 0 ) = a ( 0 + 3 ) ( 0 2 ) 2 ( 0 5 ) −2 = a ( 0 + 3 ) ( 0 2 ) 2 ( 0 5 ) −2 = 60 a a = 1 30

The graphed polynomial appears to represent the function f ( x ) = 1 30 ( x + 3 ) ( x 2 ) 2 ( x 5 ) .

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Given the graph shown in [link] , write a formula for the function shown.

Graph of a negative even-degree polynomial with zeros at x=-1, 2, 4 and y=-4.

f ( x ) = 1 8 ( x 2 ) 3 ( x + 1 ) 2 ( x 4 )

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Using local and global extrema

With quadratics, we were able to algebraically find the maximum or minimum value of the function by finding the vertex. For general polynomials, finding these turning points is not possible without more advanced techniques from calculus. Even then, finding where extrema occur can still be algebraically challenging. For now, we will estimate the locations of turning points using technology to generate a graph.

Questions & Answers

Three charges q_{1}=+3\mu C, q_{2}=+6\mu C and q_{3}=+8\mu C are located at (2,0)m (0,0)m and (0,3) coordinates respectively. Find the magnitude and direction acted upon q_{2} by the two other charges.Draw the correct graphical illustration of the problem above showing the direction of all forces.
Kate Reply
To solve this problem, we need to first find the net force acting on charge q_{2}. The magnitude of the force exerted by q_{1} on q_{2} is given by F=\frac{kq_{1}q_{2}}{r^{2}} where k is the Coulomb constant, q_{1} and q_{2} are the charges of the particles, and r is the distance between them.
Muhammed
What is the direction and net electric force on q_{1}= 5µC located at (0,4)r due to charges q_{2}=7mu located at (0,0)m and q_{3}=3\mu C located at (4,0)m?
Kate Reply
what is the change in momentum of a body?
Eunice Reply
what is a capacitor?
Raymond Reply
Capacitor is a separation of opposite charges using an insulator of very small dimension between them. Capacitor is used for allowing an AC (alternating current) to pass while a DC (direct current) is blocked.
Gautam
A motor travelling at 72km/m on sighting a stop sign applying the breaks such that under constant deaccelerate in the meters of 50 metres what is the magnitude of the accelerate
Maria Reply
please solve
Sharon
8m/s²
Aishat
What is Thermodynamics
Muordit
velocity can be 72 km/h in question. 72 km/h=20 m/s, v^2=2.a.x , 20^2=2.a.50, a=4 m/s^2.
Mehmet
A boat travels due east at a speed of 40meter per seconds across a river flowing due south at 30meter per seconds. what is the resultant speed of the boat
Saheed Reply
50 m/s due south east
Someone
which has a higher temperature, 1cup of boiling water or 1teapot of boiling water which can transfer more heat 1cup of boiling water or 1 teapot of boiling water explain your . answer
Ramon Reply
I believe temperature being an intensive property does not change for any amount of boiling water whereas heat being an extensive property changes with amount/size of the system.
Someone
Scratch that
Someone
temperature for any amount of water to boil at ntp is 100⁰C (it is a state function and and intensive property) and it depends both will give same amount of heat because the surface available for heat transfer is greater in case of the kettle as well as the heat stored in it but if you talk.....
Someone
about the amount of heat stored in the system then in that case since the mass of water in the kettle is greater so more energy is required to raise the temperature b/c more molecules of water are present in the kettle
Someone
definitely of physics
Haryormhidey Reply
how many start and codon
Esrael Reply
what is field
Felix Reply
physics, biology and chemistry this is my Field
ALIYU
field is a region of space under the influence of some physical properties
Collete
what is ogarnic chemistry
WISDOM Reply
determine the slope giving that 3y+ 2x-14=0
WISDOM
Another formula for Acceleration
Belty Reply
a=v/t. a=f/m a
IHUMA
innocent
Adah
pratica A on solution of hydro chloric acid,B is a solution containing 0.5000 mole ofsodium chlorid per dm³,put A in the burret and titrate 20.00 or 25.00cm³ portion of B using melting orange as the indicator. record the deside of your burret tabulate the burret reading and calculate the average volume of acid used?
Nassze Reply
how do lnternal energy measures
Esrael
Two bodies attract each other electrically. Do they both have to be charged? Answer the same question if the bodies repel one another.
JALLAH Reply
No. According to Isac Newtons law. this two bodies maybe you and the wall beside you. Attracting depends on the mass och each body and distance between them.
Dlovan
Are you really asking if two bodies have to be charged to be influenced by Coulombs Law?
Robert
like charges repel while unlike charges atttact
Raymond
What is specific heat capacity
Destiny Reply
Specific heat capacity is a measure of the amount of energy required to raise the temperature of a substance by one degree Celsius (or Kelvin). It is measured in Joules per kilogram per degree Celsius (J/kg°C).
AI-Robot
specific heat capacity is the amount of energy needed to raise the temperature of a substance by one degree Celsius or kelvin
ROKEEB
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Source:  OpenStax, Algebra and trigonometry. OpenStax CNX. Nov 14, 2016 Download for free at https://legacy.cnx.org/content/col11758/1.6
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