Thread: #5) Find the x-value of all pints where the function has relative extrema...

Find the x-value of all points where the function has relative extrema. Find the values of any relative extrema.

f(x)=x^3-12x+2
y'=3x^2-12=0
y'=3x^2=12
y'=x^2=4

Now after this point what i did was take the square root of each side. Now aren't i supposed to end up with +/- 2 and find the matching y-values? I get:
Max:0@-2
Min:0@2
But the computer say this is wrong i know that 0@2 is right but where did i go wrong?

Originally Posted by plstevens

Find the x-value of all points where the function has relative extrema. Find the values of any relative extrema.

f(x)=x^3-12x+2
y'=3x^2-12=0
y'=3x^2=12
y'=x^2=4

Now after this point what i did was take the square root of each side. Now aren't i supposed to end up with +/- 2 and find the matching y-values? I get:
Max:0@-2
Min:0@2
Mr F says: I have no idea what the above notation is meant to mean.

But the computer say this is wrong i know that 0@2 is right but where did i go wrong?

Stationary points at x = 2 or x = -2.

Minimum turning point at x = 2 and maximum turning point at x = -2.

min and max are for the relative maximum, and the relative minimum

Originally Posted by plstevens

min and max are for the relative maximum, and the relative minimum

I am aware of that. I was referring to the 0@-2 and 0@2 business. Try to use standard mathematical notation if you want people to make sense of what you post.

well that's how my teacher posted it, i was very unaware that this was incorrect, sorry if i confused you, but are you able to help

it just means 0 at 2, 0 being y and 2 being x

Originally Posted by plstevens

well that's how my teacher posted it, i was very unaware that this was incorrect, sorry if i confused you, but are you able to help

See reply #2.

i think its relative minimum of 0 at 2, thats how it is in the anwer choice

Originally Posted by plstevens

i think its relative minimum of 0 at 2, thats how it is in the anwer choice

. The minimum value at x = 2 is NOT 0.

The problem, as you posted it, was "Find the x-value of all points where the function has relative extrema". Those x values are -2 and 2. The problem did not ask for the corresponding y values.