Math Problem Statement

\int \frac{1}{2-\sqrt{3x}}dx

Solution

We need to evaluate the integral:

I=123xdxI = \int \frac{1}{2 - \sqrt{3x}} \, dx

Step 1: Substitution

Let’s use a substitution to simplify the square root expression. Set:

u=3xu = \sqrt{3x}

Then, differentiate uu with respect to xx:

du=123x3dx=323xdxdx=23dudu = \frac{1}{2\sqrt{3x}} \cdot 3 \, dx = \frac{3}{2\sqrt{3x}} \, dx \quad \Rightarrow \quad dx = \frac{2}{3} \, du

Also, since u=3xu = \sqrt{3x}, we have x=u23x = \frac{u^2}{3}.

Step 2: Rewrite the integral

Substitute these into the integral:

I=12u23duI = \int \frac{1}{2 - u} \cdot \frac{2}{3} \, du

Simplifying:

I=2312uduI = \frac{2}{3} \int \frac{1}{2 - u} \, du

Step 3: Solve the integral

This is a standard integral of the form 1audu\int \frac{1}{a - u} \, du, which equals lnau-\ln |a - u|. So:

12udu=ln2u\int \frac{1}{2 - u} \, du = -\ln |2 - u|

Thus, the integral becomes:

I=23(ln2u)+C=23ln2u+CI = \frac{2}{3} \cdot (-\ln |2 - u|) + C = -\frac{2}{3} \ln |2 - u| + C

Step 4: Back-substitute u=3xu = \sqrt{3x}

Finally, substitute u=3xu = \sqrt{3x} back into the expression:

I=23ln23x+CI = -\frac{2}{3} \ln |2 - \sqrt{3x}| + C

Final Answer:

I=23ln23x+C\boxed{I = -\frac{2}{3} \ln |2 - \sqrt{3x}| + C}

Would you like any additional details or explanations?

Here are some related questions you can explore:

  1. How do you handle integrals involving square roots in general?
  2. What is a common substitution technique for integrals like this?
  3. How would the result change if the integrand had a different constant inside the square root?
  4. What is the significance of the absolute value in the logarithmic result?
  5. Can this technique be applied to more complex functions inside the integral?

Tip: Always check if a substitution can simplify the expression involving roots or powers.

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Math Problem Analysis

Mathematical Concepts

Integration
Substitution Method
Logarithmic Integration

Formulas

\int \frac{1}{a - u} \, du = -\ln |a - u| + C
u = \sqrt{3x}, \quad dx = \frac{2}{3} \, du

Theorems

Substitution Theorem for Integrals

Suitable Grade Level

Undergraduate Calculus