What is the integral from 7 to 9 of 1/(x^2-25) ?

The integral from 7 to 9 of 1/(x^2-25) is -(ln(7/12))/(10)

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integral from 7 to 9 of 1/(x^2-25)

\int_{7}^{9} \frac{1}{x ^{2} - 25} d x

- \frac{ln ( \frac{7}{12} )}{10}

Decimal

0.05389 \dots

Solution steps

\int_{7}^{9} \frac{1}{x ^{2} - 25} d x

Apply Integral Substitution

= \int_{\frac{7}{5}}^{\frac{9}{5}} \frac{1}{5 ( u ^{2} - 1 )} d u

Take the constant out:

\int a \cdot f (x) d x = a \cdot \int f (x) d x

= \frac{1}{5} \cdot \int_{\frac{7}{5}}^{\frac{9}{5}} \frac{1}{u ^{2} - 1} d u

Factor

u^{2} - 1 : - (- u^{2} + 1)

= \frac{1}{5} \cdot \int_{\frac{7}{5}}^{\frac{9}{5}} \frac{1}{- ( - u ^{2} + 1 )} d u

Take the constant out:

\int a \cdot f (x) d x = a \cdot \int f (x) d x

= \frac{1}{5} (- \int_{\frac{7}{5}}^{\frac{9}{5}} \frac{1}{- u ^{2} + 1} d u)

Use the common integral:

\int \frac{1}{- u ^{2} + 1} d u = \frac{ln ∣ u + 1 ∣}{2} - \frac{ln ∣ u - 1 ∣}{2}

= \frac{1}{5} (- [\frac{ln ∣ u + 1 ∣}{2} - \frac{ln ∣ u - 1 ∣}{2}]_{\frac{7}{5}}^{\frac{9}{5}})

Simplify

\frac{1}{5} (- [\frac{ln ∣ u + 1 ∣}{2} - \frac{ln ∣ u - 1 ∣}{2}]_{\frac{7}{5}}^{\frac{9}{5}}) : - \frac{1}{5} [\frac{ln ∣ u + 1 ∣ - ln ∣ u - 1 ∣}{2}]_{\frac{7}{5}}^{\frac{9}{5}}

= - \frac{1}{5} [\frac{ln ∣ u + 1 ∣ - ln ∣ u - 1 ∣}{2}]_{\frac{7}{5}}^{\frac{9}{5}}

Compute the boundaries:

\frac{ln ( \frac{14}{5} ) - ln ( \frac{4}{5} ) - ln ( \frac{12}{5} ) + ln ( \frac{2}{5} )}{2}

= - \frac{1}{5} \cdot \frac{ln ( \frac{14}{5} ) - ln ( \frac{4}{5} ) - ln ( \frac{12}{5} ) + ln ( \frac{2}{5} )}{2}

Simplify

= - \frac{ln ( \frac{7}{12} )}{10}

f (x) = \frac{1}{10} + x e^{- x}

\frac{0.6 t ^{2} - t + 3}{t ^{2} + 3}

\frac{d}{d x} (8 x - 1)

10 x y y^{^{'}} = 1 - y^{2}

x \to \infty lim (\frac{x ^{3} + 9 x}{6 x ^{3} - x ^{2} + 3})

What is the integral from 7 to 9 of 1/(x^2-25) ?
The integral from 7 to 9 of 1/(x^2-25) is -(ln(7/12))/(10)