Question
Question: Let f(x) = 2<sup>2x–1</sup> and f(x) = –2<sup>x</sup> + 2x log 2. If f´(x) \>f¢(x), then...
Let f(x) = 22x–1 and f(x) = –2x + 2x log 2. If f´(x) >f¢(x), then
A
0 < x < 1
B
0 £ x < 1
C
x > 0
D
x ³ 0
Answer
x > 0
Explanation
Solution
f´(x) > f´(x)
22x-1.2 log 2 > 2x log 2 + 2 log 2
22x > – 2x + 2
22x + 2x – 2 > 0
(2x – 1)+ve(2x+2) > 0
2x – 1 > 0 Ž 2x > 1 Ž 2x > 20 Ž x > 0