I'v quistion on Quadratic Functions

[megatronic]

Homework Statement

Let f(x)= 125x-6x² find the maximum value of f to four decimal places graphically

Homework Equations

(x)= 125x-6x²

The Attempt at a Solution

Homework Statement

attempt solution:

x=-b+\sqrt{}b²-4ac/2a

x=-125+\sqrt{}125²-4(-6)(0)/2a

x= 0/-12=0

x=-b-\sqrt{}b²-4ac/2a

x=-b-\sqrt{}b²-4ac/2a

x=(-125-125)/-12

x=-125/6

Homework Equations

The Attempt at a Solution

 

[snshusat161]

Do you know how to make graph for quadratic equations?

 

[snshusat161]

and also show your attempt otherwise nobody will help you here because of the rules of PF

 

[megatronic]

Do you know how to make graph for quadratic equations?

ya I know to make graph for quadratic

 

[Mentallic]

Ok then, do you realize there is a symmetry of any parabola on either end of its max/min? So if you find the roots of the quadratic, what can you deduce about the coordinates of the max/min from that?

 

[Mark44]

Homework Statement

Let f(x)= 125x-6x² find the maximum value of f to four decimal places graphically

Homework Equations

(x)= 125x-6x²

The Attempt at a Solution

Homework Statement

attempt solution:

x=-b+\sqrt{}b²-4ac/2a

x=-125+\sqrt{}125²-4(-6)(0)/2a

x= 0/-12=0

x=-b-\sqrt{}b²-4ac/2a

x=-b-\sqrt{}b²-4ac/2a

x=(-125-125)/-12

x=-125/6

What you've done is attempt to find the x-intercepts, which is not at all what this problem is asking for. In addition, there is one intercept that you did not find, and the one you found is incorrect.

 

[Angry Citizen]

Think what 'maximum' is. Note that maximum does not refer to an x value.

There is a formula to determine the maximum or minimum value of a parabola. Give it a hard think. It'll come to you.

 

[Mark44]

Think what 'maximum' is. Note that maximum does not refer to an x value.

There is a formula to determine the maximum or minimum value of a parabola. Give it a hard think. It'll come to you.

The OP is not supposed to use a formula. He/she is supposed to find the maximum by looking at a graph of the function.