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Mathematics 7 Online
OpenStudy (thephysicsman):

what is the relationship between these two graphs?

OpenStudy (thephysicsman):

\[y = A(1-e^{-kx})\] \[y = Ae^{-kx}\]

OpenStudy (thephysicsman):

how would we get from one of these graphs to the other?

OpenStudy (thephysicsman):

like I know they are not inversely related @triciaal

OpenStudy (triciaal):

was thinking logs don't remember much

OpenStudy (triciaal):

@jim_thompson5910 will you please help with this, thanks

OpenStudy (thephysicsman):

Well, I guess if we took the inverse of the second equation i'm wondering if it would lead to this. \[x = Ae^{-ky}\] \[\frac{ x }{ A } = e^{-ky}\] \[\log(\frac{ x }{ A }) = \log(e^{-ky})\] \[\log(x)-\log(A) = -ky\] \[\frac{ -1 }{ k }(\log(x)-\log(A) = y)\]

OpenStudy (welshfella):

you can write the first one as A - Ae^(-kt) I think they are asking for the transformation of y = Ae^-kt to this graph

jimthompson5910 (jim_thompson5910):

\[\Large y = A(1-e^{-kx})\] \[\Large y = A-A*e^{-kx}\] \[\Large y = -A*e^{-kx}+A\]

OpenStudy (welshfella):

which will be a reflection and a translation

OpenStudy (welshfella):

- can you see what those are?

OpenStudy (thephysicsman):

question: is this a reflection about A?

OpenStudy (thephysicsman):

nvm, I think the graph is shifted up by A units

OpenStudy (welshfella):

Hint what is the transform of x^2 to -x^2?

OpenStudy (thephysicsman):

well let me see like that would make all y values negative (x,y) --> (x,-y) across the x axis because the y values become negative.

OpenStudy (welshfella):

Yes the translation part is an upward shift of A units

OpenStudy (thephysicsman):

ok cool, at least I got that part lol

OpenStudy (welshfella):

yea 1. reflection in x-axis 2 . translation A units upwards

OpenStudy (thephysicsman):

Okay Now I see what you did Jim so like the first part involved re-writing the second equation \[A-Ae^{-kx} => -Ae^{-kx}+A\]

OpenStudy (thephysicsman):

\[f(x)+C\] up by C units

OpenStudy (thephysicsman):

Now after that I see what's happening now \[f(x) <=> -f(x)\]

OpenStudy (thephysicsman):

\[-Ae^{-kx} , Ae^{-kx}\] thanks guys

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