PLEASE HELP? let g be the function given by g (x) = 3x^4 - 8x^3. At what value of x on the closed interval [ -2,2 ] does g have an absolute maximum

When we have a function g(x)

We will have a maximum at x when:

g'(x) = 0

g''(x) < 0.

Now we start with:

g(x) = 3*x^4 - 8*x^3

The first derivation is:

g'(x) = 4*3*x^3 - 3*8*x^2

g'(x) = 12*x^3 - 24*x^2

We can rewrite this as:

g'(x) = x^2*(12*x - 24)

Now we want to solve:

g'(x) = 0 =  x^2*(12*x - 24)

We have one trivial solution, that is when x = 0.

The other solution will be when the term inside of the parentheses is equal to zero.

Then we need to solve:

12*x - 24 = 0

12*x = 24

x = 24/12 = 2

Then g'(x) is equal to zero for x = 0, and x = 2.

Notice that both of these points are included in the interval [ -2,2 ]

Now we need to look at the second derivative of g(x):

g''(x) = 3*12*x^2 - 2*24*x

g''(x) = 36*x^2 - 48*x

Ok, now we need to evaluate this in the two roots we found before:

if x = 0:

g''(0) = 36*0^2 - 48*0 = 0

g''(0) = 0

Then we do not have a maximum at x = 0, this is a point of inflection.

if x = 2:

g''(2) = 36*(2^2) - 48*2 = 48

then:

g''(2) > 0

This is an absolute minimum.

Now let's look only at the interval [ -2,2 ]

We know that:

g''(0) =  0

g''(2) > 0

Then at some point, we should have g''(x) < 0 in our interval.

We need to find the first point such that happens, so let's try with the lower limit of the interval but with the first derivation, if g'(x) < 0, this means that the function is decreasing from that point on, then that point will be a maximum in our interval.

x = -2

g'(-2) = (-2)^2*(12*-2 - 24) = -192

And if we look at the function:

g'(x) = x^2*(12*x - 24)

We can easily see that it is negative unitl x = 0, and then it keeps being negative until x = 2.

So in the interval  [ -2,2 ], the function g'(x) is always negative or zero, this means that in the interval  [ -2,2 ], the function g(x) is always decreasing or constant.

Then the absolute maximum of g(x) in the interval  [ -2,2 ]  will be  x = -2

this means that:

g(-2) ≥ g(x) for all x ∈  [ -2,2 ]

b: |12 – x| ≤ 0.25

step-by-step explanation:      

let x be the possible lengths in inches, of the ribbons jaime cut.

we have been given that jaime is cutting strips of ribbon for a project. he tries to cut each piece to be 12 inches long, but sometimes he cuts it too long or too short by as much as 0.25 inch.  

we can represent this information in an inequality as:

by the definition of absolute value function we will get,

upon combining our inequalities we will get,

therefore, the inequality   describes all the possible lengths (x), in inches, of the ribbons jaime cut.

step-by-step explanation: