Q. Find the value of ∫487−2x10dx. Express your answer as a constant times ln3.Answer: □ln3
Identify the integral: Identify the integral to be solved.We need to evaluate the integral of the function 7−2x10dx from 4 to 8.
Simplify the integral: Simplify the integral.Let's use a substitution method to simplify the integral. We can let u=7−2x, which means du=−2dx or dx=−2du.
Change limits of integration: Change the limits of integration. When x=4, u=7−2(4)=−1. When x=8, u=7−2(8)=−9. So the new limits of integration are from u=−1 to u=−9.
Rewrite integral in terms of u: Rewrite the integral in terms of u.The integral becomes:∫−1−9u10⋅(−21)du=−5∫−1−9u1du.
Evaluate the integral: Evaluate the integral.The integral of u1du is ln∣u∣. So we have:−5[ln∣u∣] from −1 to −9.
Apply limits of integration: Apply the limits of integration. −5[ln∣−9∣−ln∣−1∣]=−5[ln(9)−ln(1)]=−5ln(9).Since ln(1)=0, it simplifies to −5ln(9).
Simplify the expression: Simplify the expression.We know that ln(9) is the same as 2ln(3), so the integral simplifies to:−5×2ln(3)=−10ln(3).
Express answer as constant times ln(3): Express the answer as a constant times ln(3). The final answer is −10ln(3).
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