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If the area covered by y=(2)/(x) and y=(...

If the area covered by `y=(2)/(x)` and `y=(2)/(2x-1)` from `x=1 or x=e` is ln (a) sq. units, then `(2e-1)^(2)a^(2)` is equal to

A

`(e)/(2)`

B

`e^(4)`

C

1

D

e

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The correct Answer is:
To solve the problem, we need to find the area between the curves \( y = \frac{2}{x} \) and \( y = \frac{2}{2x - 1} \) from \( x = 1 \) to \( x = e \). We will follow these steps: ### Step 1: Set up the area between the curves The area \( A \) between the two curves from \( x = 1 \) to \( x = e \) can be expressed as: \[ A = \int_{1}^{e} \left( \frac{2}{x} - \frac{2}{2x - 1} \right) \, dx \] ### Step 2: Calculate the integral We will break this integral into two parts: \[ A = \int_{1}^{e} \frac{2}{x} \, dx - \int_{1}^{e} \frac{2}{2x - 1} \, dx \] #### Part 1: Calculate \( \int_{1}^{e} \frac{2}{x} \, dx \) \[ \int \frac{2}{x} \, dx = 2 \ln |x| \] Evaluating from \( 1 \) to \( e \): \[ \left[ 2 \ln x \right]_{1}^{e} = 2 \ln e - 2 \ln 1 = 2 \cdot 1 - 0 = 2 \] #### Part 2: Calculate \( \int_{1}^{e} \frac{2}{2x - 1} \, dx \) Let \( u = 2x - 1 \), then \( du = 2 \, dx \) or \( dx = \frac{du}{2} \). When \( x = 1 \), \( u = 1 \) and when \( x = e \), \( u = 2e - 1 \). Now, substituting: \[ \int_{1}^{e} \frac{2}{2x - 1} \, dx = \int_{1}^{2e - 1} \frac{2}{u} \cdot \frac{du}{2} = \int_{1}^{2e - 1} \frac{1}{u} \, du \] \[ = \left[ \ln |u| \right]_{1}^{2e - 1} = \ln(2e - 1) - \ln(1) = \ln(2e - 1) \] ### Step 3: Combine the results Now, substituting back into the area formula: \[ A = 2 - \ln(2e - 1) \] ### Step 4: Set equal to \( \ln(a) \) Given that \( A = \ln(a) \), we can equate: \[ \ln(a) = 2 - \ln(2e - 1) \] Using properties of logarithms: \[ \ln(a) = \ln(e^2) - \ln(2e - 1) = \ln\left(\frac{e^2}{2e - 1}\right) \] Thus, we have: \[ a = \frac{e^2}{2e - 1} \] ### Step 5: Calculate \( (2e - 1)^2 a^2 \) Now we need to find \( (2e - 1)^2 a^2 \): \[ a^2 = \left(\frac{e^2}{2e - 1}\right)^2 = \frac{e^4}{(2e - 1)^2} \] Thus: \[ (2e - 1)^2 a^2 = (2e - 1)^2 \cdot \frac{e^4}{(2e - 1)^2} = e^4 \] ### Final Answer The value of \( (2e - 1)^2 a^2 \) is: \[ \boxed{e^4} \]
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Knowledge Check

  • The area bounded by y=(1)/(x) and y=(1)/(2x-1) from x = 1 to x = 2 is ln (a) sq. units, then 3a^(2) is equal to

    A
    `(1)/(2)`
    B
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    C
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    B
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    C
    ` 1-4 log_(e) 2`
    D
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    A
    `e^(e )ln (16)`
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