Finding the Area Between y=x^2 and y=-x from 0 to 2: Solution and Verification

In summary, the conversation was about finding the area between the graphs of y=x^2 and y=-x from x=0 to x=2. After some initial confusion about the boundaries and function, it was determined that the correct integral to evaluate was from x=0 to x=2 of x^2 + x. This resulted in an answer of 14/3, which was confirmed by evaluating the function at the two limits. Ultimately, the mistake was due to not properly setting up the integral and using the wrong function.
  • #1
kenny87
23
0
I am to find the area of the region between the graphs of y=x^2 and y=-x from x=0 to x=2

I evaluated the integral from 0 to 2 of x^2 - -x
I got 14/3

Is this correct?
 
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  • #2
are you sure the function is y=-x?
 
  • #3
yeah, i just double checked them. y=x^2 and y= -x
 
  • #4
if you draw the two functions, there is no area to integrate between those curves for those limits. I am kind confused why they would say from x=0 to x=2.
I setup the problem, and evaluated the integral with respect to y
and got 1/6.

i said, integral from y=1 to y = 0 and y^(.5)-y dy
 
  • #5
I think that they're going for the area beneath x^2 and above -x with the boundaries of x=0 and x=2.

I know 1/6 isn't the correct answer because its not one of the choices...
the choices are

2/3, 8/3, 4, 14/3, and 16/3

these are ap problems and i know they try to trick you though, so I am really not sure if my answer is correct or not... i might have made up some math
 
  • #6
ooooh, i am sorry.. yeah then your integral ends up being x^3/3 - x^2/2
and when you put the limits in the answer should be 2/3.
(2)^3/3-2^2/2 = 2/3
 
  • #7
can you explain to me the process you used to get that?

what i did:

1/3*x^3 - 1/2*x^2 and then evaluated it at 2 and 0... what did i do wrong?
 
  • #8
arr, stupid mistake..
lets call f(x)=x^2 and g(x)=-x
then integral from f(x)-g(x) = x^2+x
integrate that function
and we get x^3/+x^2/2
plug in the limits
and we get 14/3..
sorry for the wrong answer sheesh.. i feel dumb.
 
  • #9
no problem. thank you so much!
 

1. What is the purpose of finding the area between two functions?

The purpose of finding the area between two functions is to calculate the enclosed area or region that is bounded by the two functions. This can be useful in various scientific and mathematical applications, such as determining the total volume of a shape or finding the probability of an event occurring.

2. How do you solve for the area between two functions?

To solve for the area between two functions, you first need to find the points of intersection between the two functions. Then, you can use the definite integral to calculate the area under the curve between these points. In this case, the definite integral would be ∫(x2 - (-x))dx, with the limits of integration being from 0 to 2.

3. What is the significance of the limits of integration in this problem?

The limits of integration in this problem (0 to 2) represent the x-values of the points of intersection between the two functions. These limits determine the range over which the definite integral will be evaluated, and therefore, the area that will be calculated.

4. How can you verify the solution for the area between two functions?

One way to verify the solution for the area between two functions is to graph the functions and visually check if the calculated area matches the actual enclosed area. Additionally, you can also use numerical methods, such as the midpoint rule or trapezoidal rule, to approximate the area and compare it to the calculated value.

5. Are there any real-world applications for finding the area between two functions?

Yes, there are many real-world applications for finding the area between two functions. For example, in physics, this concept is used to calculate the work done by a variable force over a certain distance. In economics, it can be used to determine the total profit or loss for a company. It is also commonly used in engineering, biology, and other fields of science and mathematics.

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