JEE Main2018MathematicsIndefinite IntegrationActual
If ∫ tan x 1 + tan x + tan 2 x d x = x - K A tan - 1 K tan x + 1 A + C , ( C is a constant of integration), then the ordered pair K , A is equal to
Options
- A2 , 1
- B2 , 3
- C- 2 , 1
- D- 2 , 3
Correct answer
B. 2 , 3
Step-by-step solution
Let I = ∫ tan x 1 + tan x + tan 2 x d x ⇒ I = ∫ 1 - sec 2 x 1 + tan x + tan 2 x d x ⇒ I = x - ∫ d t 1 + t + t 2 Where, tan x = t ⇒ sec 2 x d x = d t ∴   I = x - 1 3 2 tan - 1 t + 1 2 3 2 + C , where C is the constant of integration. = x - 2 3 tan - 1 2 tan x + 1 3 + C ∴   K = 2   &   A = 3 .