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Mathematics 22 Online
OpenStudy (askme12345):

Finding standard function?

OpenStudy (askme12345):

1) y=f3(x)=e^x-2 2)y=f4(x)=ln(x+2) 3)y=f5(x)=-x^3+1

OpenStudy (askme12345):

@jim_thompson5910

jimthompson5910 (jim_thompson5910):

the first one is this right? \[\Large y = f_3(x) = e^{x-2}\] or is it this? \[\Large y = f_3(x) = e^{x}-2\]

OpenStudy (askme12345):

the second! \[(e^x)-2\]

jimthompson5910 (jim_thompson5910):

ok and what instructions did the professor post for this one? s/he said to graph this? and to find the standard form?

OpenStudy (askme12345):

just graph and identify a point, i figured finding standard form was part of the proccess

jimthompson5910 (jim_thompson5910):

oh no need for standard form if all you need is a point or two to find any point, you first plug in any x value you want. This x value must be in the domain of f(x) the good news is that the domain of (e^x) - 2 is the set of all real numbers

jimthompson5910 (jim_thompson5910):

an easy x value is 0 y = (e^x) - 2 y = (e^0) - 2 ... replace every x with 0 y = 1 - 2 ... x^0 = 1 where x is nonzero y = -1 So when x = 0, the value of y is y = -1 Therefore, we know that the point (0,-1) is on the graph of y = (e^x) - 2

jimthompson5910 (jim_thompson5910):

does that make sense?

OpenStudy (askme12345):

Yes it does! so for the second and 3 i could just go ahead and plug any value for x and plot

jimthompson5910 (jim_thompson5910):

which x value do you want to plug in?

OpenStudy (askme12345):

i can do x=-1 with y coming out to 0 and then another that would make a real #

OpenStudy (askme12345):

x=53 for example gives y=4

jimthompson5910 (jim_thompson5910):

\[\Large y = e^x - 2\] \[\Large y = e^{-1} - 2\] \[\Large y = ???\] the answer won't be y = 0

OpenStudy (askme12345):

oh sorry i have moved on to the next one!!

OpenStudy (askme12345):

for that one i did (-28,2) and (0,-1)

jimthompson5910 (jim_thompson5910):

I see

jimthompson5910 (jim_thompson5910):

so for ln(x+2) you plugged in x = 53 ?

OpenStudy (askme12345):

yes and got 4.00...

jimthompson5910 (jim_thompson5910):

y = 4.007, good

jimthompson5910 (jim_thompson5910):

What the graphing calculator (like desmos) is doing is computing a whole bunch of (x,y) pairs. Hundreds possibly thousands. Then it plots them all on the same grid. After that, it connects the dots. The more points, the more accurate the graph.

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