Q. Find the value of ∫684−x2dx. Write your answer as the logarithm of a single number in simplest form.Answer: ln(□)
Substitution Method: To solve this integral, we can use a substitution method. Let's let u=4−x, which means du=−dx. We need to adjust the integral to account for this substitution.
Adjusting Integral: Now we substitute u into the integral and adjust the limits of integration. When x=6, u=4−6=−2. When x=8, u=4−8=−4. Also, we need to substitute −du for dx, which will change the sign of the integral.The integral becomes:∫−2−4u−2du
Integrating with Respect to u: We can now integrate with respect to u. The integral of −u2du is −2ln∣u∣. We will evaluate this from −2 to −4.
Evaluating Antiderivative: Evaluating the antiderivative at the bounds gives us:−2ln∣−4∣+2ln∣−2∣
Simplifying Expression: Simplify the expression using properties of logarithms. Since the logarithm of a negative number is not defined in the real number system, we can remove the negative signs inside the logarithms because ln∣−a∣=ln∣a∣ for any positive a. This simplifies to: −2ln(4)+2ln(2)
Further Simplification: Now we use the property of logarithms that ln(ab)=b⋅ln(a) to further simplify the expression.This gives us:−2ln(22)+2ln(2)
Combining Like Terms: Simplify the expression by applying the power rule for logarithms and combining like terms.This simplifies to:−4ln(2)+2ln(2)
Final Answer: Combine the logarithmic terms to get the final answer.This gives us:−2ln(2)
Final Answer: Combine the logarithmic terms to get the final answer.This gives us:−2ln(2)We can now express the final answer as the logarithm of a single number.The final answer is:ln(2−2)
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