Q. Find the value of ∫142x−94dx. Express your answer as a constant times ln7.Answer: □ln7
Recognize standard form: Recognize the integral as a standard form. The integral ∫2x−94dx can be recognized as a standard form of the integral of a function of the form u1, which is ln∣u∣+C, where C is the constant of integration.
Perform substitution to simplify: Perform a substitution to simplify the integral.Let u=2x−9, then dxdu=2, or dx=2du. The integral becomes ∫u4⋅(2du).
Simplify the integral: Simplify the integral.The integral simplifies to 2∫(u1)du, which is 2ln∣u∣+C.
Substitute back for u: Substitute back for u. Substitute back u=2x−9 into the integral to get 2ln∣2x−9∣+C.
Evaluate definite integral: Evaluate the definite integral from 1 to 4. We need to evaluate 2ln∣2x−9∣ from x=1 to x=4. This gives us 2ln∣2(4)−9∣−2ln∣2(1)−9∣, which simplifies to 2ln∣8−9∣−2ln∣2−9∣.
Simplify expression: Simplify the expression.Since ln∣8−9∣=ln∣1∣=0 and ln∣2−9∣=ln∣−7∣=ln∣7∣ (because the natural logarithm function is even), the expression simplifies to 0−2ln∣7∣.
Final answer: Simplify the final answer.The final answer is −2ln∣7∣, which can be expressed as −2ln7 because 7 is positive and we do not need the absolute value.
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