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Mathematics 8 Online
OpenStudy (anonymous):

Can someone help us figure out this problem please.

OpenStudy (anonymous):

I cannot figure out which answer it is because it seems like none of them are right?

ganeshie8 (ganeshie8):

\[\large y = f(x) \longrightarrow y=kf(x) \]

ganeshie8 (ganeshie8):

its a vertical stretch if |k| > 1

ganeshie8 (ganeshie8):

and here, both functions have k = 3/2

OpenStudy (anonymous):

I thought one side is 1/2 and the other side is 1.5?

ganeshie8 (ganeshie8):

push 1/2 inside the abs bars

OpenStudy (anonymous):

I totally get it now. Thanks.

ganeshie8 (ganeshie8):

or factor out 3 : \[f(x) = \dfrac{1}{2}|3x-7|-2\] \[f(x) = \dfrac{3}{2}\Big|x-\frac{7}{3}\Big|-2\]

ganeshie8 (ganeshie8):

this can be obtained from its parent graph \(\large y = |x|\) by doing below sequence of transformations : 1) shift Left by 7/3 units 2) vertical stretch by a factor of 3/2 3) shift down by 2 units

OpenStudy (anonymous):

Right. Very cool. I didn't distribute the 1/2 into the absolute value signs properly at all and didn't see that it brought it to be 3/2 on both sides as a vertical stretch...

OpenStudy (anonymous):

Take my medal away, I did this wrong!

ganeshie8 (ganeshie8):

haha my medals are not free ;) you deserve it lol

ganeshie8 (ganeshie8):

also i think the order in which we do transformations matter

ganeshie8 (ganeshie8):

for example : 1) left shift by 2 units 2) vertical stretch by 5 units gives different functions when we change the order

OpenStudy (anonymous):

So what is the rule of the order?

ganeshie8 (ganeshie8):

there is no rule... we can interpret a graph in many ways

OpenStudy (anonymous):

There is no order by which we apply the translations on a function to graph it properly? I thought you just said if you change the order you get a different graph? Well which is the correct graph?

ganeshie8 (ganeshie8):

|dw:1405229616627:dw|

ganeshie8 (ganeshie8):

above is one example where the order DOESN't matter : 1) horizontal translation by m units 2) vertical translation by n units lets see another example where the order matters, and where we can interpret the graph in several ways depending on the order in which we do the transofrmaiton

OpenStudy (anonymous):

Aiight

ganeshie8 (ganeshie8):

y = 2|x-3| + 2 this can be interpreted in atleast two different ways. First : 1) shift right by 3 units 2) vertical stretch by 2 units 3) shift UP by `2` units Second : 1) shift right by 3 units 2) shift UP by `1` unit 3) vertical stretch by 2 units

ganeshie8 (ganeshie8):

Notice that, both sequence of transformations are referring to the same graph, but if you change the order, you will get a different graph.

OpenStudy (anonymous):

Right... so which is the real graph?

ganeshie8 (ganeshie8):

what do you mean by a real graph - First, and Second sequence of transformations lead you to SAME graph

ganeshie8 (ganeshie8):

just two different ways of interpreting the same graph

ganeshie8 (ganeshie8):

yes I am going to say that next

OpenStudy (anonymous):

Sorry! Please say it >_<

ganeshie8 (ganeshie8):

change the order in First sequence. you will get a different graph. First(NOT same) : 1) shift right by 3 units 3) shift UP by 2 units 2) vertical stretch by 2 units

ganeshie8 (ganeshie8):

I have swapped 2) and 3) steps - this produces a different graph

OpenStudy (anonymous):

Wait.. so the order does make different graphs... -_-

ganeshie8 (ganeshie8):

Exactly ! if you simply change the order, you will get different graphs most of the time. Notice that in the First and Second sequence of transformations which we did earlier, we changed both the order and also `the individual transformation` - thats the reason, both are referring to the same graph

OpenStudy (anonymous):

So back to my original question. How do we know which order to apply the operations so we come to the correct graph in the end?

ganeshie8 (ganeshie8):

again it doesn't matter - when u change the order, you will be changing the individual transformation also.

ganeshie8 (ganeshie8):

y = 2|x-3| + 2 this can be interpreted in atleast two different ways. First : 1) shift right by 3 units 2) vertical stretch by 2 units 3) shift UP by 2 units Second : 1) shift right by 3 units 2) shift UP by 1 unit 3) vertical stretch by 2 units

ganeshie8 (ganeshie8):

Both are correct ways of interpreting the given transformation. Notice that the `shift UP` is not same in both the interpretations

OpenStudy (anonymous):

You are driving me batty @ganeshie8.

ganeshie8 (ganeshie8):

ikr..

OpenStudy (anonymous):

Lol

OpenStudy (anonymous):

Ok, stick with me here. I totally get that the order that we apply the operations yields different graphs in the end. But only one of the graphs will be correct. Right?

ganeshie8 (ganeshie8):

let me put it like this : I have x : 1) add 3 : x+3 2) multiply 5 : (x+3)*5

OpenStudy (anonymous):

So far so good

ganeshie8 (ganeshie8):

now change the order in which you performed things : I have x : 2) multiply 5 : 5x 1) add 3 : 5x+3

ganeshie8 (ganeshie8):

thats the only thing i have been failing to say o,o

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