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Let f(x) be a polynomial of degree three...

Let f(x) be a polynomial of degree three `f(0) = -1 and f(1) = 0.` Also, 0 is a stationary point of `f(x).` If f(x) does not have an extremum at `x=0,` then the value of integral `int(f(x))/(x^3-1)dx,` is

A

`(x^(2))/(2)+C`

B

x+C

C

`(x^(3))/(6)+C`

D

nome of these

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the value of the integral \[ \int \frac{f(x)}{x^3 - 1} \, dx \] given the conditions on the polynomial \( f(x) \). ### Step 1: Define the polynomial \( f(x) \) Since \( f(x) \) is a polynomial of degree 3, we can express it in the general form: \[ f(x) = ax^3 + bx^2 + cx + d \] ### Step 2: Use the given conditions We have the following conditions: 1. \( f(0) = -1 \) 2. \( f(1) = 0 \) 3. \( 0 \) is a stationary point, meaning \( f'(0) = 0 \). From \( f(0) = -1 \): \[ f(0) = d = -1 \] So, we can rewrite \( f(x) \) as: \[ f(x) = ax^3 + bx^2 + cx - 1 \] ### Step 3: Apply the second condition \( f(1) = 0 \) Now, substituting \( x = 1 \): \[ f(1) = a(1)^3 + b(1)^2 + c(1) - 1 = 0 \] This simplifies to: \[ a + b + c - 1 = 0 \quad \Rightarrow \quad a + b + c = 1 \quad \text{(Equation 1)} \] ### Step 4: Use the stationary point condition The derivative of \( f(x) \) is: \[ f'(x) = 3ax^2 + 2bx + c \] Setting \( f'(0) = 0 \): \[ f'(0) = c = 0 \] Now substituting \( c = 0 \) into Equation 1: \[ a + b + 0 = 1 \quad \Rightarrow \quad a + b = 1 \quad \text{(Equation 2)} \] ### Step 5: Determine the coefficients Now we have two equations: 1. \( c = 0 \) 2. \( a + b = 1 \) We can express \( b \) in terms of \( a \): \[ b = 1 - a \] Thus, we can express \( f(x) \) as: \[ f(x) = ax^3 + (1 - a)x^2 - 1 \] ### Step 6: Choose a specific value for \( a \) Since we need \( f(x) \) to not have an extremum at \( x = 0 \), we can choose \( a = 1 \) (as an example). Then: \[ b = 1 - 1 = 0 \] Thus, we have: \[ f(x) = x^3 - 1 \] ### Step 7: Evaluate the integral Now we need to evaluate: \[ \int \frac{f(x)}{x^3 - 1} \, dx = \int \frac{x^3 - 1}{x^3 - 1} \, dx \] This simplifies to: \[ \int 1 \, dx = x + C \] ### Final Answer The value of the integral is: \[ \int \frac{f(x)}{x^3 - 1} \, dx = x + C \]

To solve the problem, we need to find the value of the integral \[ \int \frac{f(x)}{x^3 - 1} \, dx \] given the conditions on the polynomial \( f(x) \). ...
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