Let , R be such that the function f(x) = cases 2 (x2 - 2 ) + 2 x, & x < 1 \ ( + 3)x + ( - ), & x 1 cases be differentiable at all x R. Then 34( + ) is equal to
- 48
- 84
- 36
- 24
Answer
(1) 48
Solution
Continuity at x = 1:
2 (1 - 2) + 2 = ( + 3) + ( - )
-2 + 2 = 2 + 3 - 4 - 3 = -3 ...(i)
Differentiability at x = 1: LHD = 4 x + 2 |x=1 = 4 + 2 , RHD = + 3
4 + 2 = + 3 3 + 2 = 3 ...(ii)
Solving (i) and (ii): = 317, = 2117
34( + ) = 34 2417 = 48
Answer: (1)