Question

Help Please!!!!



Below is a graph that represents the total profits for a third month. Write the equation of the line that represents this graph. Show your work or explain how you determined the equations.

Answer 1

do you mean slope equation? or something else

Answer 2

okay,\[ \frac{ y-y }{ x-x} \]

is it this one?

Answer 3

y=300-(300/450)x
that's right?

Answer 4

okay then?

Answer 5

how do I create equation and find total profit

Answer 6

?

Answer 7

(0,300) and (450,0) I get this one but I am stuck at finding the total profits and creating the equation

Answer 8

to create the equation use the points (450,0) and (0,300)
then by equation
(y-y1)/(x-x1)=(y2-y1)/(x2-x1)

Answer 9

this isnt suppose to be (0, 450)? I think (450,0) is undefine

Answer 10

@tkhunny can you help me?

Answer 11

okay @esamalaa can you show me?

Answer 12

@whpalmer4 @Destinymasha

Answer 13

y1=0
y2=300
x1=450
x2=0
substitute in the general equation
then you will got
y=300-(300/450)x

Answer 14

okay, so how do I find the total profits?

Answer 15

I don't believe the question (as you have stated it) asks you to do anything but write an equation for that line. You've done that: \[y = -\frac{2}{3}x + 300\]

Answer 16

Without knowing more about the graph (like what quantities the axes represent) I don't believe you can do anything more.

Answer 17

To recap: you can find the slope of the graph by using the slope formula
\[m = \frac{y_2-y_1}{x_2-x_1}\]
where arbitrarily I choose \((x_1,y_1) = (0,300)\) and \((x_2,y_2) = (450,0)\)

\[m = \frac{0-300}{450-0} = -\frac{300}{450} = -\frac{2}{3}\]
(I like to choose \((x_1,y_1)\) to be the point on the left, so I can have a bit of a safety check that I don't do the \(y\) values in one order and the \(x\) values in the other, which would give me an incorrect slope)

Now you have a couple of options to write the equation of the line:
1) use point-slope formula with one of the points (I use the first one here, but any point will work)

\[y - y_1 = m(x-x_1)\]\[y-300=-\frac{2}{3}(x-0)\]\[y=-\frac{2}{3}x+300\]
2) because you have the y-intercept value (point where \(x=0\) is the y-intercept), you can write the answer directly using the slope-intercept form:
\[y=mx+b\]\[y = -\frac{2}{3}x+b\]\[b \text{ is the \(y\) value of the y-intercept, or \(300\)}\]\[y = -\frac{2}{3}x+300\]

Answer 18

Thanks so much for help @whpalmer4 !!!! :)

Answer 19

You're welcome!