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If int x^(2) ln x dx = (x^(3))/(m) ln x ...

If `int x^(2) ln x dx = (x^(3))/(m) ln x + (x^(3))/(n) + c`, then what are the values of m and n respectively ?
where c is a constant od intergration

A

`(1)/(3) - (1)/(9)`

B

`3, -9`

C

`3, 9`

D

`3, 3`

Text Solution

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To solve the integral \( \int x^2 \ln x \, dx \) and find the values of \( m \) and \( n \) in the expression \[ \int x^2 \ln x \, dx = \frac{x^3}{m} \ln x + \frac{x^3}{n} + c, \] we can use integration by parts. ### Step 1: Set up integration by parts Let: - \( u = \ln x \) (then \( du = \frac{1}{x} \, dx \)) - \( dv = x^2 \, dx \) (then \( v = \frac{x^3}{3} \)) ### Step 2: Apply integration by parts formula Using the integration by parts formula \( \int u \, dv = uv - \int v \, du \): \[ \int x^2 \ln x \, dx = \left( \ln x \cdot \frac{x^3}{3} \right) - \int \left( \frac{x^3}{3} \cdot \frac{1}{x} \right) dx \] ### Step 3: Simplify the integral The integral simplifies to: \[ \int x^2 \ln x \, dx = \frac{x^3}{3} \ln x - \int \frac{x^3}{3} \cdot \frac{1}{x} \, dx \] \[ = \frac{x^3}{3} \ln x - \frac{1}{3} \int x^2 \, dx \] ### Step 4: Solve the remaining integral Now, compute \( \int x^2 \, dx \): \[ \int x^2 \, dx = \frac{x^3}{3} + C \] Substituting this back, we get: \[ \int x^2 \ln x \, dx = \frac{x^3}{3} \ln x - \frac{1}{3} \left( \frac{x^3}{3} \right) + C \] \[ = \frac{x^3}{3} \ln x - \frac{x^3}{9} + C \] ### Step 5: Compare with the given expression Now we compare this with the expression given in the question: \[ \int x^2 \ln x \, dx = \frac{x^3}{m} \ln x + \frac{x^3}{n} + c \] From our result, we have: \[ \frac{x^3}{3} \ln x - \frac{x^3}{9} + C \] This implies: - \( \frac{1}{m} = \frac{1}{3} \) → \( m = 3 \) - \( \frac{1}{n} = -\frac{1}{9} \) → \( n = -9 \) ### Final Answer Thus, the values of \( m \) and \( n \) are: \[ m = 3, \quad n = -9 \]

To solve the integral \( \int x^2 \ln x \, dx \) and find the values of \( m \) and \( n \) in the expression \[ \int x^2 \ln x \, dx = \frac{x^3}{m} \ln x + \frac{x^3}{n} + c, \] we can use integration by parts. ...
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