If f(x) is decreasing for every x > 5, then which choice is not a possibility for f'(x)?
a) f'(x) = x-5
b) f'(x) = 5-x
c) f'(x) = -x^2+10x-25
d) f'(x) = -5
I chose a, am I correct?
Correct, Julius !!!!
For all x > 5, x - 5 will be positive, thus increasing.....
Also [ don't worry about how I arrived at this ] ....if x - 5 is the derivative, then (1/2)x^2 - 5x + some constant is the parent function....as shown here, no matter the added constant, this function always increases when x > 5