• Want to level up your HSC prep on those harder Maths questions?
    Register now for the BoS Trials (7th October)!

Increasing function (1 Viewer)

machine2035

Member
Joined
Mar 21, 2012
Messages
65
Gender
Male
HSC
N/A
as.jpg

Guessing it has something to do with f'(x) > 0 ?

I got as far as finding f'(x) and thats it.

Cheers.
 

Carrotsticks

Retired
Joined
Jun 29, 2009
Messages
9,467
Gender
Undisclosed
HSC
N/A
We indeed want f'(x) > 0, for all x.

So we differentiate f(x) (we get a quadratic), then let the discriminant be less than zero. By doing this, you always have the quadratic being positive and hence f'(x) > 0.
 

machine2035

Member
Joined
Mar 21, 2012
Messages
65
Gender
Male
HSC
N/A
We indeed want f'(x) > 0, for all x.

So we differentiate f(x) (we get a quadratic), then let the discriminant be less than zero. By doing this, you always have the quadratic being positive and hence f'(x) > 0.
Awesome, cheers.

Ended up getting k < 3
 

Users Who Are Viewing This Thread (Users: 0, Guests: 1)

Top