# 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

(x)= 125x-6x2

## 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

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## Answers and Replies

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

Homework Helper
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?

Mentor

## Homework Statement

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

(x)= 125x-6x2

## 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.

Mentor
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.