Question

I don't understand this, would like help

http://prntscr.com/dk0zlb

Answer 1

Just identify the interval where the line is below the parabola, the enpoint of the interval must contain the values on the x-axis.

Answer 2

isn't it where the two graphs intersect?

Answer 3

Yes we will use that as the endpoints, but will we use () or [] in writing the intervals?
Take note that if we include the endpoints it means the cost is equal to revenue.

Answer 4

You need to write the equation of the parabola and the line first..
Take note of the form: y = a(x - h)^2 + k.

Answer 5

In writing the equation of the line, you could use the form:
\[y - y_1 = \frac{y_2-y_1}{x_2-x_1}(x - x_1)\]

Answer 6

we would use []
and I got the equation as of the parabola as y=-50x^2+1000x and the linear as y=30x+1000

Answer 7

I tried graphing it for the points of intersection but it didn't work ...

Answer 8

oh, we would use ( ), because it's less than

Answer 9

Yes, the () is correct, since we are asked about the number of products that would lead to less cost than revenues.

Answer 10

The equations that you have are correct!

Answer 11

But I can't find the points where the two functions intersect...

Answer 12

Are you allowed to use technology for this?

Answer 13

yeaah, I input the functions on my calculator, but I didn't find the intersects

Answer 14

I tried it on mine, and it worked..
Are you using a ti-83/ti-84?

Answer 15

ti-84

Answer 16

is the x value a decimal..?

Answer 17

yes..

Answer 18

But, we could round it up, since we are talking about quantities here.

Answer 19

Do you have something like that on the WINDOW before graphing it?

Answer 20

Oh... no, this calculator is my sister's old one and I have no clue how to use it xD

Answer 21

How do you do that?

Answer 22

Ohhhh nevermind, I see

Answer 23

You need to press WINDOW and adjust it to those numbers first.
After pressing WINDOW input 0 for Xmin, then press ENTER,
input 20 for XMAS, and press ENTER, input 10 for Xscl and press ENTER.
Input 0 for Ymin and press ENTER and input 2000 for Ymax and input 100 for Yscl.

Answer 24

The two equations you got look good,
y=-50x^2+1000x
y=30x+1000

To see where they intersect if they do you can set them equal..

-50x^2 + 1000x = 30x + 1000

Answer 25

Yes, you could also do that.. finding it algebraically.

Answer 26

x=18.3 and x= 1.09?

Answer 27

Exactly!

Answer 28

I also tried it algebraically ...

Answer 29

looks right, just use those x values to get the corresponding y values for the points

Answer 30

No need to find the y-values, since we need the intervals for the number of products that will lead to less cost than revenue.

Answer 31

\[\frac{ 970\pm \sqrt{940900-4(50000)} }{ -100 }\] ?

Answer 32

So the answer would be written as (1.09, 18.3)?
and im trying to solve it algebraically again

Answer 33

Yes, that is correct!

Answer 34

Oh... I found out why I got the wrong answer while solving it algebraically... I multiplied incorrectly :P Thanks guys!

Answer 35

The problem is about products produced, i think you should round to the next highest quantity, so no partial products are represented

2 to 18

Answer 36

You're welcome! Keep it up! Pleasure helping you.

Answer 37

If you will do that, you need to include the 2 and 18 though, so [2, 18].

Answer 38

Wouldn't it be better to round it down because it needs to be below revenue?

Answer 39

My bad

Answer 40

up for the first, and down for the second, to keep inside the parabola and have cost less than revenue

Answer 41

Nevermind, that sounds right xD

Answer 42

Thanks :)

Answer 43

You're welcome, God bless you both! :)

Answer 44

Ahh thanks for the help, I almost ripped out my hair xD