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Find the value of 
int_(4)^(8)(10 dx)/(7-2x). Express your answer as a constant times 
ln 3.
Answer: 
◻ln 3

Find the value of 4810dx72x \int_{4}^{8} \frac{10 d x}{7-2 x} . Express your answer as a constant times ln3 \ln 3 .\newlineAnswer: ln3 \square \ln 3

Full solution

Q. Find the value of 4810dx72x \int_{4}^{8} \frac{10 d x}{7-2 x} . Express your answer as a constant times ln3 \ln 3 .\newlineAnswer: ln3 \square \ln 3
  1. Identify the integral: Identify the integral to be solved.\newlineWe need to evaluate the integral of the function 10dx72x\frac{10 \, dx}{7-2x} from 44 to 88.
  2. Simplify the integral: Simplify the integral.\newlineLet's use a substitution method to simplify the integral. We can let u=72xu = 7 - 2x, which means du=2dxdu = -2 dx or dx=du2dx = -\frac{du}{2}.
  3. Change limits of integration: Change the limits of integration. When x=4x = 4, u=72(4)=1u = 7 - 2(4) = -1. When x=8x = 8, u=72(8)=9u = 7 - 2(8) = -9. So the new limits of integration are from u=1u = -1 to u=9u = -9.
  4. Rewrite integral in terms of u: Rewrite the integral in terms of u.\newlineThe integral becomes:\newline1910(12)duu=5191udu\int_{-1}^{-9} \frac{10 \cdot (-\frac{1}{2}) \, du}{u} = -5 \int_{-1}^{-9} \frac{1}{u} \, du.
  5. Evaluate the integral: Evaluate the integral.\newlineThe integral of 1udu\frac{1}{u} \, du is lnu\ln|u|. So we have:\newline5[lnu]-5 [\ln|u|] from 1-1 to 9-9.
  6. Apply limits of integration: Apply the limits of integration. \newline5[ln9ln1]=5[ln(9)ln(1)]=5ln(9)-5 [\ln|-9| - \ln|-1|] = -5 [\ln(9) - \ln(1)] = -5 \ln(9).\newlineSince ln(1)=0\ln(1) = 0, it simplifies to 5ln(9)-5 \ln(9).
  7. Simplify the expression: Simplify the expression.\newlineWe know that ln(9)\ln(9) is the same as 2ln(3)2 \ln(3), so the integral simplifies to:\newline5×2ln(3)=10ln(3)-5 \times 2 \ln(3) = -10 \ln(3).
  8. Express answer as constant times ln(3)\ln(3): Express the answer as a constant times ln(3)\ln(3). The final answer is 10ln(3)-10 \ln(3).

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