Exponential Function:
A population of a city is P = 250342e0.012t where t represent the population in the year 2000.
Find the total population of the city in the year 2010.
To find the population in the year 2010 you have to let t = 10 giving you the equation
P = 250342e0.012(10) which equals 282259.82
Now this graph on the left is not the real graph to this equation but this is what it would look like. The numbers on the y-axis would have a much greater value because of the high population growth while the numbers on the x-axis would stay about the same because you are counting by years. Also the angle of elevation would be much great creating a sharper curve.
http://www.algebralab.org/lessons/lesson.aspx?file=Algebra_ExponentsApps.xml
Linear Equation:
A company purchases a computer for $10000. Use a linear graph to show the depreciation of the computer over a 5 year period if each year the computer the depreciates $2000 a year.
The equation for this problem can be modeled by Y = -2000x+10000.
On the right is the graph of this equation. You put the number of years in the x value in the equation. You can see that after one year the value of the computer is $8000 and after two years the value of the computer is at $6000.
http://hubpages.com/hub/APPLICATIONS--OF-LINEAR-EQUATIONS
Quadratic Equations:
A producer of personal computer mouse covers determines that the number (N) of covers sold is related to the price (x) of a cover by N = 35x-x^2. At what price should the producer price a mouse cover in order to sell 216 of these items.
What you would do is sub in 216 for N. 216 = 35x-x^2. Move the 216 to the right side of the equation and then solve. You should have answers of x = 8 and x = 27. You will put those back in the equation for x and solve again. In this case both of these x values are correct so you will be order to price them at $8 or $27 to sell 216.
This example doesn't have a graph for an example but generally all x^2 graphs will have a U-shape to them.
http://cnx.org/content/m21915/latest/