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The integral ∫2dxe2x−1\int \frac{2dx}{e^{2x}-1} is equal to:

Solution

✅ Correct Option: 4

The integral ∫2dxe2x−1\int \frac{2dx}{e^{2x}-1}

Let u=e2xu = e^{2x}

Then dudx=2e2x=2u\frac{du}{dx} = 2e^{2x} = 2u

So dx=du2udx = \frac{du}{2u}


∫2dxe2x−1=∫2u−1⋅du2u\int \frac{2dx}{e^{2x}-1} = \int \frac{2}{u-1} \cdot \frac{du}{2u}

=∫duu(u−1)= \int \frac{du}{u(u-1)}


1u(u−1)=Au+Bu−1\frac{1}{u(u-1)} = \frac{A}{u} + \frac{B}{u-1}

1=A(u−1)+Bu1 = A(u-1) + Bu

Put u=0u = 0:

1=A(−1)1 = A(-1)

A=−1A = -1

Put u=1u = 1:

1=B(1)1 = B(1)

B=1B = 1

Therefore 1u(u−1)=−1u+1u−1\frac{1}{u(u-1)} = \frac{-1}{u} + \frac{1}{u-1}


∫duu(u−1)=∫−1udu+∫1u−1du\int \frac{du}{u(u-1)} = \int \frac{-1}{u}du + \int \frac{1}{u-1}du

=−ln⁡∣u∣+ln⁡∣u−1∣+C= -\ln|u| + \ln|u-1| + C

=ln⁡∣u−1∣−ln⁡∣u∣+C= \ln|u-1| - \ln|u| + C

=ln⁡∣u−1u∣+C= \ln\left|\frac{u-1}{u}\right| + C


Substituting u=e2xu = e^{2x} back:

=ln⁡∣e2x−1e2x∣+C= \ln\left|\frac{e^{2x}-1}{e^{2x}}\right| + C

Therefore, the integral equals log⁡∣e2x−1e2x∣+C\log\left|\frac{e^{2x}-1}{e^{2x}}\right| + C

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