Machine-translated by Google. Questions are authored in English.
Top

Discussion

The value of \(\int_{0}^{3} x^{2}[x]\,dx\) is equal to

  • A.18
  • B.15
  • C.12
  • D.10
  • E.8

Answer: B

The value is 15.

The greatest integer \([x]\) is 0, 1 and 2 on [0, 1), [1, 2) and [2, 3).

\[ \begin{aligned} \int_{0}^{3}x^{2}[x]\,dx &= 0 + \int_{1}^{2}x^{2}dx + 2\int_{2}^{3}x^{2}dx \\ &= \tfrac{7}{3} + 2 \times \tfrac{19}{3} = \tfrac{45}{3} = 15 \end{aligned} \]

Without the factor [x] the integral would be 9. Forgetting the 2 on the last piece gives \(\frac{26}{3}\), and treating [x] as x gives \(\frac{81}{4}\).

No comment is present. Be the first to comment.
Loading…

Post your comment

Please log in or register to post a comment.