Highly selective Backlog Qs for JEE MainMathematicsLimits
The value of l i m x → 0 c o s tan x - cos x 4 x 4 is equal to
Options
- A- 1 3
- B- 1 12
- C1 2
- D1
Correct answer
B. - 1 12
Step-by-step solution
c o s tan x - cos x = 2 s i n x + tan x 2 s i n x - tan x 2 ⇒ l i m x → 0 c o s tan x - cos x 4 x 4 = l i m x → 0 2 s i n x + tan x 2 s i n x - tan tan x 2 4 x 4 = l i m x → 0 2 s i n x + tan x 2 s i n x - tan x 2 4 x 4 x + tan x 2 x - tan x 2 x 2 - t a n 2 x 4 = 1 8 l i m x → 0 x 2 - t a n 2 x x 4 = 1 8 l i m x → 0 x 2 - x + x 3 3 + 2 15 x 5 + . . . . 2 x 4 = 1 8 l i m x → 0 1 x 2 1 - 1 + x 2 3 + 2 15 x 4 + . . . . 2 = - 1 12