Math Problem Statement

integrate ((3cosx-2)sinx)/(5-sin^2x-4cosx) dx

Solution

To solve the integral

(3cosx2)sinx5sin2x4cosxdx,\int \frac{(3\cos x - 2)\sin x}{5 - \sin^2 x - 4\cos x} \, dx,

we can approach it using substitution. Let's define:

u=5sin2x4cosx.u = 5 - \sin^2 x - 4\cos x.

First, we need to find the derivative of uu with respect to xx:

dudx=2sinxcosx+4sinx.\frac{du}{dx} = -2\sin x \cos x + 4\sin x.

Notice that this can be factored as:

dudx=sinx(2cosx+4).\frac{du}{dx} = \sin x(-2\cos x + 4).

This closely resembles the numerator of the integrand. However, the numerator is (3cosx2)sinx(3\cos x - 2)\sin x, so let's rewrite the integral in terms of dudu:

(3cosx2)sinx5sin2x4cosxdx.\int \frac{(3\cos x - 2)\sin x}{5 - \sin^2 x - 4\cos x} \, dx.

Using the substitution u=5sin2x4cosxu = 5 - \sin^2 x - 4\cos x, the integral becomes:

(3cosx2)2cosx+4dusinx(2cosx+4).\int \frac{-(3\cos x - 2)}{-2\cos x + 4} \frac{du}{\sin x(-2\cos x + 4)}.

Simplifying further:

duu.\int \frac{du}{u}.

This integral is straightforward:

lnu+C,\ln |u| + C,

where u=5sin2x4cosxu = 5 - \sin^2 x - 4\cos x. So the final answer is:

ln5sin2x4cosx+C.\ln |5 - \sin^2 x - 4\cos x| + C.

Would you like more details or have any questions?

Here are some related questions:

  1. How do you perform trigonometric substitutions in integrals?
  2. What are common strategies for solving integrals involving trigonometric functions?
  3. How do you recognize a function that is suitable for uu-substitution?
  4. Can you generalize the integral approach for functions involving both sine and cosine?
  5. How does the chain rule assist in evaluating integrals by substitution?

Tip: When dealing with integrals involving trigonometric functions, look for patterns or identities that can simplify the integrand before integrating.

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Math Problem Analysis

Mathematical Concepts

Integral Calculus
Trigonometric Substitution

Formulas

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Theorems

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Suitable Grade Level

College Level