Math Problem Statement

Evaluate the indefinite integral ∫ 7sin^3(x)cos(x) dx.

Solution

The integral provided in the image is:

7sin3(x)cos(x)dx\int 7 \sin^3(x) \cos(x) \, dx

Solution:

  1. Simplify the Integral: Notice that the integral can be simplified by a substitution. Let’s use the substitution: u=sin(x)u = \sin(x) Then, du=cos(x)dxdu = \cos(x) \, dx

  2. Rewrite the Integral: Substitute uu and dudu into the integral: 7sin3(x)cos(x)dx=7u3du\int 7 \sin^3(x) \cos(x) \, dx = 7 \int u^3 \, du

  3. Integrate: The integral of u3u^3 with respect to uu is: u44\frac{u^4}{4} Therefore: 7u3du=7u44=7u447 \int u^3 \, du = 7 \cdot \frac{u^4}{4} = \frac{7u^4}{4}

  4. Substitute Back: Now substitute u=sin(x)u = \sin(x) back into the expression: 7u44=7sin4(x)4\frac{7u^4}{4} = \frac{7 \sin^4(x)}{4}

  5. Add the Constant of Integration: Don’t forget to add the constant of integration CC: 7sin4(x)4+C\frac{7 \sin^4(x)}{4} + C

Final Answer:

7sin3(x)cos(x)dx=7sin4(x)4+C\int 7 \sin^3(x) \cos(x) \, dx = \frac{7 \sin^4(x)}{4} + C

Would you like further details or have any questions?

Here are some related questions to consider:

  1. What substitution would you use if the integral was 5sin2(x)cos(x)dx\int 5 \sin^2(x) \cos(x) \, dx?
  2. How would the solution change if the integral was sin3(x)cos(x)dx\int \sin^3(x) \cos(x) \, dx without the constant 7?
  3. What is the general formula for integrating sinn(x)cos(x)dx\sin^n(x) \cos(x) \, dx?
  4. How would you handle the integral sin3(x)cos2(x)dx\int \sin^3(x) \cos^2(x) \, dx?
  5. What other integration techniques could apply if the powers of sine and cosine were different?

Tip: When dealing with powers of trigonometric functions, substitution using basic trigonometric identities often simplifies the integral significantly.

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Math Problem Analysis

Mathematical Concepts

Calculus
Integration
Trigonometric Substitution

Formulas

∫ u^n du = (u^(n+1))/(n+1) + C
Substitution u = sin(x), du = cos(x) dx

Theorems

Integration by Substitution

Suitable Grade Level

Grades 11-12