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Mathematics 8 Online
OpenStudy (anonymous):

Compare the functions shown below.

OpenStudy (anonymous):

Which function has the greatest y-intercept? (2 points) f(x) g(x) h(x) All three functions have the same y-intercept.

OpenStudy (e.mccormick):

Don't know what f, g, and h are. However, if you look at them mathematically, you should be able to find the y intercepts.

OpenStudy (anonymous):

Help?

OpenStudy (e.mccormick):

Like I said, I don't know what f, g, and h are. How can I help if I do not know what the fuctions are?

OpenStudy (anonymous):

The functions are in the graph attached

OpenStudy (anonymous):

@VeritasVosLiberabit

OpenStudy (anonymous):

gamer mccormick is looking for the actual function eg. y=x

OpenStudy (anonymous):

They didn't give me that just a graph

OpenStudy (anonymous):

they can do anything if you don't know the function itself

OpenStudy (e.mccormick):

I see 5 lines in the attached graph, none of which have any markings as to which function they are.

OpenStudy (anonymous):

f(x) = 4x + 5 h(x) = 3 sin(2x + π) - 2

OpenStudy (anonymous):

Those are definitely not the same funtions as in the picture

OpenStudy (anonymous):

That is what they gave

OpenStudy (anonymous):

Maybe you have to assume that the functions have asymptotes and approach some x value

OpenStudy (anonymous):

If that is the case the only thing I could say is the middle one has the largest y-intercept. But I have no idea which funtion that corresponds to

OpenStudy (anonymous):

OpenStudy (e.mccormick):

In a linear function: \(y=mx+b\) the b is the y intercept In the sine fuction \(y=A\sin(x+h)+b\) the b is the y intercept It changes for others, but in those two, the b spot is what you need to look at.

OpenStudy (anonymous):

See second attachment

OpenStudy (anonymous):

g(x)

OpenStudy (e.mccormick):

And for g(x), well, you can see the y intercept on that agraph.

OpenStudy (anonymous):

So is the answer B then?

OpenStudy (e.mccormick):

Well, given what I have pointed out, what are thr three y intercepts?

OpenStudy (anonymous):

I am not sure? How do I plug it in?

OpenStudy (e.mccormick):

Start with the \(f(x) = 4x + 5 \). What is the y intercept for that? It is a linear equation and should be the simplest one.

OpenStudy (anonymous):

5

OpenStudy (e.mccormick):

OK. So, the next one is the graph of \(g(x)\) Where does that intercept y?

OpenStudy (anonymous):

I am not sure really?

OpenStudy (e.mccormick):

It is on the graph. Where does it hit the y axis?

OpenStudy (anonymous):

Not sure

OpenStudy (e.mccormick):

Can you see the y axis on the picture?

OpenStudy (anonymous):

I don't know

OpenStudy (e.mccormick):

OK. The x axis or abscissa is the horizontal line with numbers on it. In this case, they are assorted things with \(\pi\) in them. The y axis or ordinate is the vertical line with numbers on it. In this case, they are integers. |dw:1400969270847:dw|

OpenStudy (anonymous):

At (0,2)

OpenStudy (e.mccormick):

Yes. It has to do with the definition of a function. For any X value there is 1 and only one Y value. So it can't loop over off the shown part of the graph and mess you up because they told you it is a function.

OpenStudy (e.mccormick):

OK. So, what is the y intercept of the last one? The fact it is shifted might make it a little tricky.

OpenStudy (anonymous):

Don't know, this is taking really long and I have 41 assignments with questions like these

OpenStudy (e.mccormick):

There is some logic you can use if you know what the amplitude of the trig function is.

OpenStudy (anonymous):

explain

OpenStudy (anonymous):

The hx one has a y intercept of -2

OpenStudy (e.mccormick):

On sine, the amplitude tells you the highest and lowest points before things are shifted. So on \(A\sin x\) A is the amplitude. If it was say 20, then the highest and lowest points would be 20 and -20 before any shifts. On yours it is 3. And the shift at the end of yours is -2. So, the highest point that graph ever reaches is 3-2=1. No matter what the y int is, it can not be more than 1.

OpenStudy (e.mccormick):

So, of 5, 2, and -2, which is the highest y intercept?

OpenStudy (anonymous):

So it is A

OpenStudy (e.mccormick):

Yep. https://www.desmos.com/calculator/q6cyithltk

OpenStudy (anonymous):

I have another question

OpenStudy (anonymous):

How do I solve this, I don't know what g(x) is?

OpenStudy (anonymous):

Is it A?

OpenStudy (e.mccormick):

See what \((0,y_1)\) and \((4,y_2)\) for each function. Then do \(|y_2-y_1|\) that will get you the average rate of change for those functions over that period. The reason I use the absolute value is because you want rate of change, not rate and direction.

OpenStudy (anonymous):

fx rate of change is 64

OpenStudy (e.mccormick):

Yes.

OpenStudy (anonymous):

gx is -2

OpenStudy (anonymous):

Don't know what hx is

OpenStudy (e.mccormick):

That is rate and direction. For just rate it is 2.

OpenStudy (e.mccormick):

\(h(x)=(x+4)^2+2\) \(h(0)=(0+4)^2+2\) \(h(0)=(4)^2+2\) and \(h(4)=(4+4)^2+2\) \(h(4)=(8)^2+2\) Find those.

OpenStudy (anonymous):

hx=48

OpenStudy (anonymous):

Help?

OpenStudy (anonymous):

D is the answer

OpenStudy (e.mccormick):

Well, g(x) is changing slowest, and f(x) the fastest.

OpenStudy (anonymous):

I have more

OpenStudy (anonymous):

Is it h(x)?

OpenStudy (e.mccormick):

Trig functions will be different, but for the \(x^n+x^{n-1}+...+x+k\) functions, the MOST they will have is n intercepts with the x axis. So the higest degree is the most they could have. They can also have less if they have a hump that just touches or does not touch.

OpenStudy (anonymous):

So how do I solve this?

OpenStudy (e.mccormick):

Well, you can use that fact to know the most that h(x) has. Then look at f(x) and g(x).

OpenStudy (fionacndg):

Does anyone know which function had the most intercepts

OpenStudy (e.mccormick):

Well, did you look at what I suggested to them for how to solve it?

OpenStudy (fionacndg):

yea, it doesn't matter right now, i thought it was fx but that was wrong.

OpenStudy (maddielb):

For future people the answer was h(x)!

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