Definite IntegrationHard
Question
The value of the function f (x) = 1 + x +
(ln2t + 2 lnt) dt, where f′(x) vanishes is:
Options
A. e-1
B.0
C.2 e-1
D.1 + 2 e-1
Solution
1 + ln2x + 2ln x = 0
⇒ x =
Let ln t = z ⇒ 1/t dt = dz ⇒ dt = ez dz
∴
= 1+
= 
= 1 +
= 1 + 
⇒ x =
Let ln t = z ⇒ 1/t dt = dz ⇒ dt = ez dz
∴
= 1 +
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