Questions: Evaluate the integral ∫ from -∞ to -7 of (2/(2x-3)^2) dx or state that the integral diverges. Express your answer in simplest form.
Transcript text: Evaluate the integral $\int_{-\infty}^{-7} \frac{2}{(2 x-3)^{2}} d x$ or state that the integral diverges. Express your answer in simplest form.
Solution
Solution Steps
Step 1: Define the Integral
We start with the improper integral we want to evaluate:
\[
\int_{-\infty}^{-7} \frac{2}{(2x-3)^{2}} \, dx
\]
Step 2: Find the Antiderivative
To evaluate the integral, we first find the antiderivative of the integrand \(\frac{2}{(2x-3)^{2}}\). The antiderivative is given by:
\[
-\frac{2}{4x - 6}
\]
Step 3: Evaluate the Definite Integral
Next, we evaluate the definite integral from a limit \(a\) approaching \(-\infty\) to \(-7\):
\[
\lim_{a \to -\infty} \left( -\frac{2}{4a - 6} - \left(-\frac{2}{4(-7) - 6}\right) \right)
\]
Step 4: Simplify the Expression
Calculating the value at the upper limit:
\[
-\frac{2}{4(-7) - 6} = -\frac{2}{-28 - 6} = -\frac{2}{-34} = \frac{1}{17}
\]
Thus, the expression simplifies to:
\[
\lim_{a \to -\infty} \left( -\frac{2}{4a - 6} + \frac{1}{17} \right)
\]
Step 5: Evaluate the Limit
As \(a\) approaches \(-\infty\), the term \(-\frac{2}{4a - 6}\) approaches \(0\). Therefore, we have:
\[
0 + \frac{1}{17} = \frac{1}{17}
\]
Step 6: Conclusion
The integral converges to:
\[
\int_{-\infty}^{-7} \frac{2}{(2x-3)^{2}} \, dx = \frac{1}{17}
\]