Math Problem Statement

Evaluate \( \int_0^2 |2x - 3| \, dx \).

Solution

To solve the integral

022x3dx,\int_0^2 |2x - 3| \, dx,

we need to analyze the behavior of the absolute value expression 2x3|2x - 3| within the given interval. This can be broken into two parts:

  1. Find where 2x3=02x - 3 = 0 within the interval [0,2][0, 2] to determine where the absolute value expression changes sign.
  2. Split the integral at this point of change and compute each segment separately.

Step 1: Determine the critical point

Solve 2x3=02x - 3 = 0: 2x=3x=32.2x = 3 \Rightarrow x = \frac{3}{2}.

This means the expression 2x32x - 3 changes sign at x=32x = \frac{3}{2}. Therefore, we split the integral at x=32x = \frac{3}{2} and rewrite it as two separate integrals:

022x3dx=032(32x)dx+322(2x3)dx.\int_0^2 |2x - 3| \, dx = \int_0^{\frac{3}{2}} (3 - 2x) \, dx + \int_{\frac{3}{2}}^2 (2x - 3) \, dx.

Step 2: Evaluate each integral separately

  1. First integral from 00 to 32\frac{3}{2}: 032(32x)dx.\int_0^{\frac{3}{2}} (3 - 2x) \, dx.

    Integrate 32x3 - 2x: (32x)dx=3xx2.\int (3 - 2x) \, dx = 3x - x^2.

    Now evaluate from 00 to 32\frac{3}{2}: [3xx2]032=(332(32)2)(3002).\left[ 3x - x^2 \right]_0^{\frac{3}{2}} = \left( 3 \cdot \frac{3}{2} - \left( \frac{3}{2} \right)^2 \right) - (3 \cdot 0 - 0^2). Simplify: =(9294)=18494=94.= \left( \frac{9}{2} - \frac{9}{4} \right) = \frac{18}{4} - \frac{9}{4} = \frac{9}{4}.

  2. Second integral from 32\frac{3}{2} to 22: 322(2x3)dx.\int_{\frac{3}{2}}^2 (2x - 3) \, dx.

    Integrate 2x32x - 3: (2x3)dx=x23x.\int (2x - 3) \, dx = x^2 - 3x.

    Now evaluate from 32\frac{3}{2} to 22: [x23x]322=(2232)((32)2332).\left[ x^2 - 3x \right]_{\frac{3}{2}}^2 = \left( 2^2 - 3 \cdot 2 \right) - \left( \left( \frac{3}{2} \right)^2 - 3 \cdot \frac{3}{2} \right). Simplify: =(46)(9492)=2(94184)=2+94=84+94=14.= (4 - 6) - \left( \frac{9}{4} - \frac{9}{2} \right) = -2 - \left( \frac{9}{4} - \frac{18}{4} \right) = -2 + \frac{9}{4} = -\frac{8}{4} + \frac{9}{4} = \frac{1}{4}.

Step 3: Combine the results

Add the results of both integrals: 94+14=104=52.\frac{9}{4} + \frac{1}{4} = \frac{10}{4} = \frac{5}{2}.

Final Answer

022x3dx=52.\int_0^2 |2x - 3| \, dx = \frac{5}{2}.

Would you like further explanation on any steps or concepts used here?

Here are five questions related to this integral:

  1. How does the absolute value affect the integration process?
  2. What would happen if the limits were different, say 032x3dx\int_0^3 |2x - 3| \, dx?
  3. Can you graph the function 2x3|2x - 3| to visually see the break point at x=32x = \frac{3}{2}?
  4. How can this method be applied to other functions with absolute values?
  5. What are other ways to handle integrals involving piecewise functions?

Tip: When integrating absolute values, identifying where the expression inside changes sign is crucial, as it allows you to split the integral and remove the absolute value by treating each interval accordingly.

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Integral Calculus
Absolute Value Functions
Definite Integrals
Piecewise Integration

Formulas

Definite integral formula \( \int_a^b f(x) \, dx \)
Handling absolute values by splitting integrals based on sign change points

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

College Calculus or Advanced High School Calculus