Improper Integrals Problem need help ! Evaluate 1/(x2 + 15x + 56) dx. You may en
ID: 2846705 • Letter: I
Question
Improper Integrals Problem need help !
Evaluate 1/(x2 + 15x + 56) dx. You may enter your answer as a formula or as a decimal. If you enter your answer as a decimal, it must be accurate to within 0.0001. If the answer is infinity or -infinity, enter +Inf or -Inf. If the answer is undefined, enter Und. Evaluate (8x2 - x - 4)exp(-4x) dx. You may enter your answer as a formula or as a decimal. If you enter your answer as a decimal, it must be accurate to within 0.0001. If the answer is infinity or -infinity, enter +Inf or -Inf. If the answer is undefined, enter Und.Explanation / Answer
1. 1/(x^2+15x+56) =1/(x+8)(x+7) =1/(x+7) - 1/(x+8)
integrating this wil give ln ((x+7)/(x+8) =
at 0 its value is ln (7/8)
at infinity it can be written as:
ln ((1+ 7/x)/(1 + 8/x)
with x =infinity it changes ln 1 =0
hence answer is 0-ln(7/8) =ln(8/7)