Solve the Integral of x - 2|x| from [-1,2] | Easy Step-by-Step Solution

  • Thread starter Shaybay92
  • Start date
  • Tags
    Integral
In summary, The given definite integral can be rewritten as the sum of two integrals, one from -1 to 0 and one from 0 to 2. By using the properties of absolute values, the absolute values can be eliminated and the integral can be solved by considering the two separate intervals. This results in an answer of -3.5.
  • #1
Shaybay92
124
0

Homework Statement



Integral[ x - 2|x|]dx from [-1,2]


The Attempt at a Solution



Wouldn't it become x^2/2 - 2x^2/2 so x^2/2 - x^2 and then -x^2/2?

So from [-1,2] it would just be

-((2^2)/2) - - ((-1)^2/2) which is -1.5 but the answer is -3.5...
 
Physics news on Phys.org
  • #2
dddd
 
  • #3
Wait, sorry this shouldn't be the issue because from my graph the whole function is negative anyway... any suggestions?
 
  • #4
I can be wrong, but I would try

[tex]\int_{-1}^2f(x)dx = \int_{-1}^0f(x)dx + \int_{0}^2f(x)dx[/tex]
 
  • #5
I agree with Borek. The idea is that you can eliminate the absolute values by looking at the integrand on [-1, 0] and on [0, 2].

If x <= 0, |x| = -x.
If x >= 0, |x| = x.
 

1. What is an integral?

An integral is a mathematical concept that represents the area under a curve on a graph. It is used to find the total value or quantity of a function over a given interval.

2. How do you solve an integral?

To solve an integral, you need to use integration techniques such as substitution, integration by parts, or trigonometric substitution. You also need to know the limits of integration, which represent the interval over which you are finding the area.

3. What does the absolute value in the integral represent?

The absolute value in an integral represents the distance from the x-axis. In the case of this integral, the absolute value of x means that the function will be positive for all values of x, regardless of whether x is positive or negative.

4. What is the step-by-step solution to this integral?

The step-by-step solution to this integral involves breaking it into two separate integrals based on the limits of integration. For the interval [-1,0], the integral of x - 2|x| is equal to (-x^2/2) - (2x^2/2) + C. For the interval [0,2], the integral of x - 2|x| is equal to (x^2/2) - (2x^2/2) + C. Combining these two solutions gives the final solution of x^2 - 2|x|^2 + C.

5. Is this integral considered easy to solve?

This integral can be considered easy to solve for those who are familiar with integration techniques. However, for those who are new to integrals, it may require some practice and understanding of the concepts involved. It is always helpful to break the integral into smaller parts and use a step-by-step approach to find the solution.

Similar threads

  • Calculus and Beyond Homework Help
Replies
10
Views
418
  • Calculus and Beyond Homework Help
Replies
7
Views
692
  • Calculus and Beyond Homework Help
Replies
15
Views
776
  • Calculus and Beyond Homework Help
Replies
14
Views
203
  • Calculus and Beyond Homework Help
Replies
3
Views
335
  • Calculus and Beyond Homework Help
Replies
10
Views
1K
  • Calculus and Beyond Homework Help
Replies
5
Views
168
  • Calculus and Beyond Homework Help
Replies
25
Views
312
  • Calculus and Beyond Homework Help
Replies
3
Views
247
  • Calculus and Beyond Homework Help
Replies
8
Views
651
Back
Top