Question

If f : R $\to$ R is defined by f(x) = 3x + |x| , then f(2x) - f (- x) - 6x =

• A. f(x)
• B. 2f(x)
• C. -f(x)
• D. f(-x)

Answer 1

Answer: (A)

f (x) = 3x+ | x |
$\therefore$ f (2x) - f (-x) - 6x
=6x+ | 2x | -3(-x)- | -x | -cx
= 3x + 2 | x | - | x | ($\because$| x |=| -x |)
= 3x + | x |= f (x)