6. The region enclosed by the graphs of \( y = e^{x/2} \) and \( y = (x - 1)^2 \) from \( x = 0 \) to \( x = 1 \) is rotated about the x-axis. What is the volume of the solid generated?






Answer is: option4

\( \left(e - \dfrac{6}{5} \right)\pi \)

Solution:

The volume when rotating about the x-axis is:

\[ V = \pi \int_0^1 \left[ \left(e^{x/2}\right)^2 - \left((x - 1)^2\right)^2 \right] dx \]

\[ V = \pi \int_0^1 \left[ e^x - (x - 1)^4 \right] dx \]

First term:

\[ \int_0^1 e^x \, dx = e^1 - e^0 = e - 1 \]

Second term:

Let \( u = x - 1 \)

  • \( du = dx \)
  • When \( x = 0 \), \( u = -1 \)
  • When \( x = 1 \), \( u = 0 \)

\[ \int_0^1 (x - 1)^4 dx = \int_{-1}^0 u^4 \, du \]

\[ \int_{-1}^0 u^4 \, du = \left[ \frac{u^5}{5} \right]_{-1}^0 = \frac{0^5}{5} - \frac{(-1)^5}{5} = 0 - \left(-\frac{1}{5}\right) = \frac{1}{5} \]

Final Volume:

\[ V = \pi \left[ (e - 1) - \frac{1}{5} \right] = \pi \left( e - \frac{6}{5} \right) \]

Option D

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