Question
Question: In the interval (1, 2), function f(x) = 2\|x – 1\| + 3\| x – 2\| is...
In the interval (1, 2), function f(x) = 2|x – 1| + 3| x – 2| is
A
Monotonic increasing
B
Monotonic decreasing
C
Not monotonic
D
Constant
Answer
Monotonic decreasing
Explanation
Solution
in x Î (1, 2)
f(x) = 2(x – 1) – 3 (x – 2) = – x + 4
f ¢(x) = – 1 < 0 " x ̃ decreasing