Determine whether a function is increasing/decreasing at given point? (1 Viewer)

[matreha]

Hi everyone,

I have a maths question:

Determine whether the curve is increasing or decreasing at the given point:

b) y = 8x^2 + 11x - 4 at (-2, 6)

What I did was differentiate it to get y' = 16x + 11
I then subbed in x=-2 and got a negative answer, so it is decreasing. This is the correct answer, but doesn't that mean that I haven't even used the 6 in (-2, 6)? Am I missing something? Why is the 6 provided if you don't need to use it?

Thanks!

 

[Squar3root]

Hi everyone,

I have a maths question:

Determine whether the curve is increasing or decreasing at the given point:

b) y = 8x^2 + 11x - 4 at (-2, 6)

What I did was differentiate it to get y' = 16x + 11
I then subbed in x=-2 and got a negative answer, so it is decreasing. This is the correct answer, but doesn't that mean that I haven't even used the 6 in (-2, 6)? Am I missing something? Why is the 6 provided if you don't need to use it?

Thanks!

yes you've done what the question says, the y value is not needed in this case

 

[Kaido]

Likely the 6 will be used in the latter part of the question