hints for graphs (directly prop., inversely prop., etc)

[Rosalindbungs]

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can anybody give me hints on how they identify relationships that are not necessarily linked by obvious equations?

i know the graphs for directly proportional, exponential, and inversely proportional, but how do graphs look if it's:

a graph linking y and a
y=x-(a*b)

or just other cases? can anybody help me out?

 

[ilovemcat]

can anybody give me hints on how they identify relationships that are not necessarily linked by obvious equations?

i know the graphs for directly proportional, exponential, and inversely proportional, but how do graphs look if it's:

a graph linking y and a
y=x-(a*b)

or just other cases? can anybody help me out?

That's so wierd that you ask that. I came online just to ask the same thing. 🙂

 

[ilovemcat]

I'm thinking you have to just memorize certain graph shapes, especially when exponents become a factor in comparison.

 

[Rabolisk]

y=x-(ab), where x and b are constants and a is the variable would be the same thing as y=mx + b rearranged, with a negative slope.

 

[thomasfx10]

I am bumping this post ...

I ordered the Official Guide to the MCAT Exam and in it is says to know the graphical representations of these dependences ...

@ = Proportional

1) y @ x
2) y @ -x
3) y @ sqrt x
4) y @ 1/x
5) y @ 1 x^2
6) y @ sin x
7) y @ cos x

Question ... Anyone know where I can get this info?

I know ...

• proportional (Linear)
• inversely proportional (slow curve)
• exponential (fast Curve)

Please add of you know or direct me to a link. Thanks!

 

[gunj122]

scroll about halfway through

http://prep.math.lsa.umich.edu/cgi-bin/pmc/crtopic?sxn=14&top=1&crssxn=prep
the graph for y=1/x^2 isn't shown, but it is simply y=1/x except that ALL Y-values are positive.

goodluck

 

[YouNeverKnow22]

I'm really having trouble with just simple graphs (especially slow curve vs. fast curve)....any help?

 

[berriesandcream]

I'm really having trouble with just simple graphs (especially slow curve vs. fast curve)....any help?

For this, I look at the slope.
Steep=faster (so in distance vs time, more distance over smaller time).
the opposite for slower.

in general, for rates I look at the slope in my head, with a larger slope meaning larger rate.

hope it helped 🙂

 

[whiteshadodw]

honestly, the "limiting cases" usually works really well. i never memorize function shapes. you can set the independent variable super high (infinity) and set it super low (zero) and usually narrow it down to one or two graphs. then, you can use the same logic but double the independent variable, and see how the dependent changes.