Math Problem Statement

HOW TO CALCULATE THIS

How to calculate the integral \( \int_0^1 x(1 - x)^2 \, dx \)?

Solution

To solve the integral:

01x(1x)2dx\int_0^1 x(1 - x)^2 \, dx

we can follow these steps:

Step 1: Expand the Integrand

Rewrite (1x)2(1 - x)^2 by expanding it:

(1x)2=12x+x2(1 - x)^2 = 1 - 2x + x^2

Thus, the integrand x(1x)2x(1 - x)^2 becomes:

x(1x)2=x(12x+x2)=x2x2+x3x(1 - x)^2 = x(1 - 2x + x^2) = x - 2x^2 + x^3

Step 2: Set Up the Integral

Now we rewrite the integral as:

01x(1x)2dx=01(x2x2+x3)dx\int_0^1 x(1 - x)^2 \, dx = \int_0^1 (x - 2x^2 + x^3) \, dx

Step 3: Integrate Term by Term

Now, integrate each term separately:

  1. 01xdx=[x22]01=12\int_0^1 x \, dx = \left[ \frac{x^2}{2} \right]_0^1 = \frac{1}{2}
  2. 012x2dx=2[x33]01=213=23\int_0^1 2x^2 \, dx = 2 \left[ \frac{x^3}{3} \right]_0^1 = 2 \cdot \frac{1}{3} = \frac{2}{3}
  3. 01x3dx=[x44]01=14\int_0^1 x^3 \, dx = \left[ \frac{x^4}{4} \right]_0^1 = \frac{1}{4}

Step 4: Combine the Results

Now we put it all together:

01(x2x2+x3)dx=1223+14\int_0^1 (x - 2x^2 + x^3) \, dx = \frac{1}{2} - \frac{2}{3} + \frac{1}{4}

Step 5: Simplify

To combine these fractions, we need a common denominator, which is 12:

12=612,23=812,14=312\frac{1}{2} = \frac{6}{12}, \quad \frac{2}{3} = \frac{8}{12}, \quad \frac{1}{4} = \frac{3}{12}

Thus,

612812+312=68+312=112\frac{6}{12} - \frac{8}{12} + \frac{3}{12} = \frac{6 - 8 + 3}{12} = \frac{1}{12}

Final Answer

01x(1x)2dx=112\int_0^1 x(1 - x)^2 \, dx = \frac{1}{12}

Would you like further details, or do you have any questions?


Here are some related questions to expand your understanding:

  1. How would the result change if the limits of integration were different?
  2. What if the integrand were x(1x)3x(1 - x)^3 instead of x(1x)2x(1 - x)^2?
  3. How does changing xx to x2x^2 in the integrand affect the solution?
  4. What is the geometric interpretation of this integral?
  5. How can integration by parts be used here, and would it simplify the calculation?

Tip: Expanding polynomials in integrals can simplify complex expressions, making integration straightforward by reducing it to basic polynomial integration.

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Math Problem Analysis

Mathematical Concepts

Integration
Polynomial Expansion

Formulas

Expansion of (1 - x)^2 = 1 - 2x + x^2
Integral of x, x^2, x^3 terms: \( \int x^n dx = \frac{x^{n+1}}{n+1} \)

Theorems

Fundamental Theorem of Calculus

Suitable Grade Level

Grades 11-12 or early university