Math Problem Statement

Solve the integral \( \int \sqrt{x}(2x - 4) \, dx \).

Solution

The given integral is:

x(2x4)dx\int \sqrt{x}(2x - 4) \, dx

Let's solve it step by step.

Step 1: Expand the expression inside the integral

We rewrite the integral: x(2x4)dx=(2xx4x)dx\int \sqrt{x}(2x - 4) \, dx = \int \left(2x\sqrt{x} - 4\sqrt{x}\right) \, dx

Step 2: Simplify terms

Recall that x=x1/2\sqrt{x} = x^{1/2}. Using the rule for multiplying exponents, xaxb=xa+bx^a \cdot x^b = x^{a+b}: 2xx=2x3/2,4x=4x1/22x\sqrt{x} = 2x^{3/2}, \quad 4\sqrt{x} = 4x^{1/2} So the integral becomes: (2x3/24x1/2)dx\int \left(2x^{3/2} - 4x^{1/2}\right) \, dx

Step 3: Integrate term by term

We use the power rule for integration: xndx=xn+1n+1,n1\int x^n \, dx = \frac{x^{n+1}}{n+1}, \quad n \neq -1

  1. For 2x3/22x^{3/2}: 2x3/2dx=2x5/25/2=4x5/25\int 2x^{3/2} \, dx = 2 \cdot \frac{x^{5/2}}{5/2} = \frac{4x^{5/2}}{5}

  2. For 4x1/2-4x^{1/2}: 4x1/2dx=4x3/23/2=8x3/23\int -4x^{1/2} \, dx = -4 \cdot \frac{x^{3/2}}{3/2} = -\frac{8x^{3/2}}{3}

Step 4: Combine results

The integral becomes: 4x5/258x3/23+C\frac{4x^{5/2}}{5} - \frac{8x^{3/2}}{3} + C

Final Answer:

x(2x4)dx=4x5/258x3/23+C\int \sqrt{x}(2x - 4) \, dx = \frac{4x^{5/2}}{5} - \frac{8x^{3/2}}{3} + C

Let me know if you'd like more details or a graph of this function. Additionally, here are five follow-up questions for practice:

  1. How would the integration change if the bounds were specified?
  2. What happens if 2x42x - 4 is replaced by another polynomial?
  3. How can we verify this solution using differentiation?
  4. How would this integral look if expressed in terms of a definite integral from x=0x=0 to x=1x=1?
  5. Can this integral be solved using substitution instead?

Tip:

Always simplify expressions before integrating to make the process easier and reduce errors!

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Math Problem Analysis

Mathematical Concepts

Integration
Exponents
Polynomial Expansion

Formulas

Power rule for integration: \( \int x^n \, dx = \frac{x^{n+1}}{n+1} \)
Exponent multiplication: \( x^a \cdot x^b = x^{a+b} \)

Theorems

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Suitable Grade Level

Grades 11-12