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int("cos"x +x "sin " x)/(x(x + cos x)) d...

`int("cos"x +x "sin " x)/(x(x + cos x)) dx` is equal to

A

`log[x(x + cos x)] + c`

B

`"log"(x/("x + cos x")) +c`

C

`"log" ((x + cos x)/(x))`

D

none of these

Text Solution

AI Generated Solution

The correct Answer is:
To solve the integral \[ \int \frac{\cos x + x \sin x}{x(x + \cos x)} \, dx, \] we can follow these steps: ### Step 1: Simplify the integrand We can rewrite the integrand by separating the terms in the numerator: \[ \frac{\cos x + x \sin x}{x(x + \cos x)} = \frac{\cos x}{x(x + \cos x)} + \frac{x \sin x}{x(x + \cos x)}. \] This simplifies to: \[ \frac{\cos x}{x(x + \cos x)} + \frac{\sin x}{x + \cos x}. \] ### Step 2: Rewrite the integral Now we can split the integral into two parts: \[ \int \frac{\cos x}{x(x + \cos x)} \, dx + \int \frac{\sin x}{x + \cos x} \, dx. \] ### Step 3: Integrate the first part For the first integral, we can use the substitution method. Let: \[ u = x + \cos x \implies du = (1 - \sin x) \, dx. \] Thus, we can rewrite the integral as: \[ \int \frac{\cos x}{x(x + \cos x)} \, dx = \int \frac{\cos x}{x u} \cdot \frac{du}{1 - \sin x}. \] However, this integral is complex, so we will focus on the second part. ### Step 4: Integrate the second part For the second integral: \[ \int \frac{\sin x}{x + \cos x} \, dx, \] we can use the substitution \(u = x + \cos x\) again. The derivative is: \[ du = (1 - \sin x) \, dx. \] Thus, we can express \(dx\) in terms of \(du\): \[ dx = \frac{du}{1 - \sin x}. \] Now, substituting back into the integral gives: \[ \int \frac{\sin x}{u} \cdot \frac{du}{1 - \sin x}. \] ### Step 5: Combine the results The two integrals can be combined, and we can simplify the results. The integral of \(\frac{1}{x}\) is \(\ln |x|\), and the integral of \(\frac{1}{u}\) is \(\ln |u|\). Thus, we have: \[ \ln |x| - \ln |x + \cos x| + C = \ln \left| \frac{x}{x + \cos x} \right| + C. \] ### Final Answer The final result of the integral is: \[ \int \frac{\cos x + x \sin x}{x(x + \cos x)} \, dx = \ln \left| \frac{x}{x + \cos x} \right| + C. \]
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Knowledge Check

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    A
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    B
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