Q. Evaluate ∫57x−82x2−17x+5dx. Write your answer in simplest form with all logs condensed into a single logarithm (if necessary).
Perform Polynomial Long Division: Perform polynomial long division to simplify the integrand.We need to divide the polynomial 2x2−17x+5 by x−8.2x2−17x+5:(x−8)=2x+1 with a remainder of 21x−3.So, (2x2−17x+5)/(x−8)=2x+1+(21x−3)/(x−8).
Write Integral with Simplified Integrand: Write the integral with the simplified integrand.Now we can write the integral as:∫57(2x+1+x−821x−3)dx.This can be split into three separate integrals:∫572xdx + ∫571dx + ∫57x−821x−3dx.
Integrate Each Term Separately: Integrate each term separately.The first integral is ∫572xdx=x2 evaluated from 5 to 7.The second integral is ∫571dx=x evaluated from 5 to 7.For the third integral, we need to split the fraction into two parts:∫57x−821xdx−∫57x−83dx.
Simplify Third Integral Further: Simplify the third integral further.The term x−821x can be rewritten as 21+x−8168 by polynomial long division.So, ∫57x−821xdx=∫5721dx+∫57x−8168dx.Now we have four integrals to evaluate:∫572xdx, ∫571dx, ∫5721dx, and ∫57x−8168−x−83dx.
Evaluate Definite Integrals: Evaluate the definite integrals.The first integral: ∫572xdx=x2 evaluated from 5 to 7 = 72−52=49−25=24.The second integral: ∫571dx=x evaluated from 5 to 7 = 7−5=2.The third integral: ∫5721dx=21x evaluated from 5 to 7 = 51.The fourth integral: 52.
Evaluate Fourth Integral: Evaluate the fourth integral.The fourth integral is ∫57x−8165dx=165⋅ln∣x−8∣ evaluated from 5 to 7.This gives us 165⋅ln∣7−8∣−165⋅ln∣5−8∣=165⋅ln∣−1∣−165⋅ln∣−3∣.Since the natural logarithm of a negative number is not defined in the real number system, we have made a mistake. We should have used the absolute value inside the logarithm.
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