Math Problem Statement

Evaluate ∫ 𝑥+1 √3𝑥−2 2 1 𝑑𝑥 using the substitution 𝑢 = 3𝑥 − 2

Solution

Let's proceed to evaluate the integral you provided:

x+13x2dx\int \frac{x+1}{\sqrt{3x-2}} \, dx

Using the substitution u=3x2u = 3x - 2, we will follow the steps below.

Step 1: Substitution

Let: u=3x2u = 3x - 2

Then, differentiate both sides with respect to xx: du=3dxordx=du3du = 3 \, dx \quad \text{or} \quad dx = \frac{du}{3}

Step 2: Express everything in terms of uu

Now, express x+1x+1 in terms of uu. From the substitution u=3x2u = 3x - 2, we can solve for xx: x=u+23x = \frac{u + 2}{3} Thus: x+1=u+23+1=u+53x + 1 = \frac{u + 2}{3} + 1 = \frac{u + 5}{3}

Also, 3x2=u\sqrt{3x - 2} = \sqrt{u}.

Step 3: Rewrite the integral

Substitute these expressions into the original integral:

x+13x2dx=u+53udu3\int \frac{x+1}{\sqrt{3x-2}} \, dx = \int \frac{\frac{u + 5}{3}}{\sqrt{u}} \cdot \frac{du}{3}

This simplifies to:

19u+5udu\frac{1}{9} \int \frac{u + 5}{\sqrt{u}} \, du

Step 4: Split the integral

Now, split the integrand into two parts:

19uudu+195udu\frac{1}{9} \int \frac{u}{\sqrt{u}} \, du + \frac{1}{9} \int \frac{5}{\sqrt{u}} \, du

This simplifies further:

19u1/2du+59u1/2du\frac{1}{9} \int u^{1/2} \, du + \frac{5}{9} \int u^{-1/2} \, du

Step 5: Integrate each term

Now, integrate each term:

  1. For the first integral: u1/2du=23u3/2\int u^{1/2} \, du = \frac{2}{3} u^{3/2}

  2. For the second integral: u1/2du=2u1/2\int u^{-1/2} \, du = 2u^{1/2}

Step 6: Combine the results

Now, substitute the results back into the integral:

19(23u3/2+52u1/2)\frac{1}{9} \left( \frac{2}{3} u^{3/2} + \frac{5}{2} u^{1/2} \right)

This simplifies to:

227u3/2+518u1/2\frac{2}{27} u^{3/2} + \frac{5}{18} u^{1/2}

Step 7: Substitute u=3x2u = 3x - 2 back

Now, substitute u=3x2u = 3x - 2 back into the result:

227(3x2)3/2+518(3x2)1/2+C\frac{2}{27} (3x - 2)^{3/2} + \frac{5}{18} (3x - 2)^{1/2} + C

So the final answer is:

x+13x2dx=227(3x2)3/2+518(3x2)1/2+C\int \frac{x+1}{\sqrt{3x-2}} \, dx = \frac{2}{27} (3x - 2)^{3/2} + \frac{5}{18} (3x - 2)^{1/2} + C

Let me know if you need further explanation or help with other problems!

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Math Problem Analysis

Mathematical Concepts

Integration
Substitution Method
Definite Integrals

Formulas

∫ u^n du = (u^(n+1)) / (n+1) + C
Substitution: If u = g(x), then du = g'(x) dx

Theorems

Fundamental Theorem of Calculus
Substitution Rule

Suitable Grade Level

Undergraduate Calculus