22.3k views
1 vote
Complete the square in the denominator, make appropriate substitution, and integrate.

∫2x-5/x²+4x+5 dx (Hint: 2x - 5 = 2x + 4-9)

User Bbonev
by
7.5k points

1 Answer

3 votes

Final answer:

To integrate ∫(2x-5)/(x²+4x+5) dx, complete the square in the denominator and make the appropriate substitution. The integral simplifies to (1/2)(2 ln|u²+1|-9 arctan(u²+1)) + C.

Step-by-step explanation:

To integrate the expression ∫(2x-5)/(x²+4x+5) dx, we can complete the square in the denominator. The quadratic expression x²+4x+5 can be rewritten as (x+2)²+1. We make the substitution u = x+2, so du = dx.

Now, our integral becomes ∫(2(u-2)-5)/(u²+1) du. Expanding and simplifying the numerator, we have ∫(2u-9)/(u²+1) du.

To integrate this expression, we use the u-substitution method. Let v = u²+1, so dv = 2u du. We can rewrite the integral as (1/2)∫(2u-9)/(u²+1) du = (1/2)∫(2u-9)/v dv. This integral can be simplified further to (1/2)∫(2/v)-9/v dv = (1/2)(2 ln|v|-9 arctan(v)) + C, where C is the constant of integration.

User Francky
by
7.8k points
Welcome to QAmmunity.org, where you can ask questions and receive answers from other members of our community.

9.4m questions

12.2m answers

Categories