ilovenyc
Which of the following inequalities matches the graph? (see attached photo)
A y _>_3x - 5
B y < 3x - 5
C y < 1/3x - 5
D The correct inequality is not listed.
Delete
Share
This Question is Closed
ilovenyc
Best Response
You've already chosen the best response.
0
srossd
Best Response
You've already chosen the best response.
0
Alright, so lets pick up where we left off. Can you find two points on the line?
ilovenyc
Best Response
You've already chosen the best response.
0
(4,7)
srossd
Best Response
You've already chosen the best response.
0
Yup, that's one, good job.
srossd
Best Response
You've already chosen the best response.
0
@ilovenyc Can you find another one?
ilovenyc
Best Response
You've already chosen the best response.
0
(2,8)
srossd
Best Response
You've already chosen the best response.
0
@ilovenyc Well, go over to 2 on the x axis, and then go up until you hit the line. What y are you at? That's how you get a point.
ilovenyc
Best Response
You've already chosen the best response.
0
(2,0)?
srossd
Best Response
You've already chosen the best response.
0
@ilovenyc Not quite, although the drawing isn't too great. (2,1) is on the line.
srossd
Best Response
You've already chosen the best response.
0
Do you see how that works?
ilovenyc
Best Response
You've already chosen the best response.
0
YES
srossd
Best Response
You've already chosen the best response.
0
Great! So now, do you remember how to find the slope?
ilovenyc
Best Response
You've already chosen the best response.
0
To find the slope m of the line segment joining the points, use the slope formula
srossd
Best Response
You've already chosen the best response.
0
Right, so try doing that with (2,1) and (4,7)
srossd
Best Response
You've already chosen the best response.
0
@ilovenyc Making any progress, or do you need some help?
ilovenyc
Best Response
You've already chosen the best response.
0
need some help do i add those both together?
srossd
Best Response
You've already chosen the best response.
0
Not quite, it's more of a subtraction. Here's the slope formula:
\[\frac{y_2-y_1}{x_2-x_1} \; \; \; x_1 = 2 \; \; \; x_2 = 4 \; \; \; y_1=1 \; \; \; y_2=7 \]
srossd
Best Response
You've already chosen the best response.
0
@ilovenyc So see if you can use that to find the slope. I'll be back in just a little bit.
ilovenyc
Best Response
You've already chosen the best response.
0
@srossd so i need to subtract that
srossd
Best Response
You've already chosen the best response.
0
@ilovenyc Just use that formula I wrote, plug in the numbers. And now I'll be back in a little bit :).
ilovenyc
Best Response
You've already chosen the best response.
0
is the answer 13?
srossd
Best Response
You've already chosen the best response.
0
No, here's another hint:
\[\frac{7-1}{4-2}\]
srossd
Best Response
You've already chosen the best response.
0
And ok, now I'm actually leaving for a little bit.
srossd
Best Response
You've already chosen the best response.
0
Just a few minutes, though.
srossd
Best Response
You've already chosen the best response.
0
@ilovenyc Alright, I'm back now. So did you get the slope from that?
ilovenyc
Best Response
You've already chosen the best response.
0
6,and 2
srossd
Best Response
You've already chosen the best response.
0
Well, 6 divided by 2.
srossd
Best Response
You've already chosen the best response.
0
So the slope ends up being 3.
srossd
Best Response
You've already chosen the best response.
0
@ilovenyc So now you know that the line will be y=3x+b. So plug in x = 0 to that, and you'll be y=b. So look at the graph, and go to the point where x=0. Find what y is.
srossd
Best Response
You've already chosen the best response.
0
|dw:1356749491751:dw|
ilovenyc
Best Response
You've already chosen the best response.
0
-4?
srossd
Best Response
You've already chosen the best response.
0
The drawing is bad again, it's actually -5. But close enough that I'm pretty sure you get it.
srossd
Best Response
You've already chosen the best response.
0
So if your equation was y=3x+b, and b=-5, what's your final equation?
ilovenyc
Best Response
You've already chosen the best response.
0
2 = 3*(-4) + b?
srossd
Best Response
You've already chosen the best response.
0
No, no - just plug in the value of b (-5) to y=3x+b. The x and y should stay.
ilovenyc
Best Response
You've already chosen the best response.
0
okay
srossd
Best Response
You've already chosen the best response.
0
@ilovenyc Do you understand, or do you need some help?
ilovenyc
Best Response
You've already chosen the best response.
0
need some help
srossd
Best Response
You've already chosen the best response.
0
Ok, so you solved for b, so just put it where b was. The equation comes out to be y=3x-5.
srossd
Best Response
You've already chosen the best response.
0
Do you see how that works, plugging in -5 for b?
ilovenyc
Best Response
You've already chosen the best response.
0
so B is the answer
srossd
Best Response
You've already chosen the best response.
0
Actually, it's A, since everything above the line is shaded. B would be the opposite shading.
ilovenyc
Best Response
You've already chosen the best response.
0
oh okay
srossd
Best Response
You've already chosen the best response.
0
But still, good job!
srossd
Best Response
You've already chosen the best response.
0
And again, sorry for elongating this so much - I just wanted to make sure you understand how to do it.
srossd
Best Response
You've already chosen the best response.
0
@ilovenyc So do you feel like you have a good grasp on how to do this type of problem now?
ilovenyc
Best Response
You've already chosen the best response.
0
@srossd i think so...
srossd
Best Response
You've already chosen the best response.
0
Alright, good. I can make up another one for you to try if you want.
ilovenyc
Best Response
You've already chosen the best response.
0
well i have more problems that i need to do on my homework
srossd
Best Response
You've already chosen the best response.
0
Oh, ok. Need help with those?
ilovenyc
Best Response
You've already chosen the best response.
0
yes
srossd
Best Response
You've already chosen the best response.
0
Ok, want to post a new problem?
srossd
Best Response
You've already chosen the best response.
0
@ilovenyc I'll be on the lookout for a new post.