The Bob
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Hello all, again.
Simple question.
Compute \int_{9}^{4} (x - \frac{1}{\sqrt{x}}) dx
I did this:
\int_{9}^{4} (x - \frac{1}{x^{0.5}}) dx = \int_{9}^{4} (x - x^{-0.5}) dx
\left[ \frac{1}{2} x^2 - 2 x^{0.5} \right]_{9}^{4} = \left[ \frac{x^2}{2} - 2 \sqrt{x} \right]_{9}^{4}
(\frac{81}{2} - 6) - (\frac{16}{2} - 4) = \frac{81 - 12}{2} - \frac{16 - 8}{2} = \frac{69}{2} - \frac{8}{2} = \frac{61}{2} = 30.5
2 months of calculus and and still I am not sure of what I have done wrong. The answers in my book gives 10 \frac{2}{3}
So if it is right then can someone enlighten me to what I have done wrong please.
Cheers
The Bob (2004 ©)
Simple question.
Compute \int_{9}^{4} (x - \frac{1}{\sqrt{x}}) dx
I did this:
\int_{9}^{4} (x - \frac{1}{x^{0.5}}) dx = \int_{9}^{4} (x - x^{-0.5}) dx
\left[ \frac{1}{2} x^2 - 2 x^{0.5} \right]_{9}^{4} = \left[ \frac{x^2}{2} - 2 \sqrt{x} \right]_{9}^{4}
(\frac{81}{2} - 6) - (\frac{16}{2} - 4) = \frac{81 - 12}{2} - \frac{16 - 8}{2} = \frac{69}{2} - \frac{8}{2} = \frac{61}{2} = 30.5
2 months of calculus and and still I am not sure of what I have done wrong. The answers in my book gives 10 \frac{2}{3}
So if it is right then can someone enlighten me to what I have done wrong please.
Cheers
The Bob (2004 ©)