Let f ¢¢(x) > 0, " x Î R and g(x) = f(2 - x) + f(4 + x),
A. (-¥, -1)
B. (-¥, 0)
C. (-1, ¥)
D. none of these
Ans: C
Sol: f ¢¢(x) > 0 " x Î R Þ f ¢(x) is increasing, " x Î R.
g ¢(x) = –f ¢(2 - x) + f ¢(4 + x)
If g ¢(x) > 0
4 + x > 2 - x
x > -1.
