Question

How do you get the answer to this problem :
A company earns a weekly profit of P dollars by selling x items, according to the equation P(x)=-5x^2+40x-300. How many items does the company have to sell each week to maximize the profit?

Answer 1

find the max, and then find that x value. do you know calculas?

Answer 2

No I don't ... I'm just in algebra 1

Answer 3

what about how to find a vertex?

Answer 4

I got 30 and 10 first. Then tried again and got -4

Answer 5

-b/(2a) will give the vertex, the y value then use that to solve for x

Answer 6

-5x^2+40x-300, so -40/(2(-5)) = 4

Answer 7

I got 4 for -b divided by 2 times negative 5

Answer 8

YeA. Got that. Thanks

But how do u find the maximum

Answer 9

this is your x value, now plug that into the function to get your y value

Answer 10

that y value is the max

Answer 11

But the answer is a negative number..... -220

Answer 12

Would -220 be the max?

Answer 13

O.. Wait I think I understand now
1 sec

Answer 14

yes that is your max
it does not make much since to me in context but thats it

Answer 15

Yea same here. Thanks. :)
Also can u please help me with this problem : the highs h in ft of a projectile launched vertically upward from the tip of a 96 foot tall tower when the time is given by t=0 is given by h=96+80t-16t^2. The object is launched when the time is 0. How LNG will it take the projectile to strike the ground? What is the maximum height that the projectile reaches?

Answer 16

set it = to -96 and solve to get the time it will take to hit the broung, and then do the same thing we did last time to get the height but this time add 96 feet

Answer 17

broung = ground

Answer 18

does this make since?

Answer 19

Not really. I am still trying to get the first part of the Answer

Answer 20

now that i look at the function it looks like it has taken into acound the 96 feet, so just set the function equal to zero and solve. do you know how to do this>?

Answer 21

I got 5 And -16 for the first part. Is that correct?

Answer 22

Yes when it's equal to zero I got -1 and 6

Answer 23

so 6 (units of time) is the answer to the first part

Answer 24

Oh ok thanks. So to fine the next part do I do what I did for the first problem

Answer 25

yes

Answer 26

it will be 196 feet

Answer 27

Wait I don't understand how u got that. Sorry

Answer 28

I got 160

Answer 29

ok so the vertex is -80/(2(-16)) = 5/2
when I plug this into the function I get 196

Answer 30

make since?

Answer 31

Yea. Thanks. So to graph that would I just...

Answer 32

you could plot all the points from 0-6 or use software to do it
http://www.wolframalpha.com/input/?i=graph+96%2B80t-16t%5E2

Answer 33

yeah?

Answer 34

O ok. And Icahn use that for the first problem too. To graph?

Answer 35

*** I can

Answer 36

sure just type it in like I did at the top

Answer 37

Thanks so much. You were a great help.

Answer 38

np you can msg me anytime for help

Answer 39

I need help with the geometry proof. > Please

Given: angle AXY is congruent to the angle AYX, and angle AXC is congruent to angle AYB

Prove: segment BY is congruent to segment CX

Answer 40

please help me with this. thank you :) if you would like me to send the pic. just let me know