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Calculus1 22 Online
OpenStudy (anonymous):

I need help on a question for exponential functions: Which of these constants could possibly be greater than the value of a?

OpenStudy (anonymous):

ganeshie8 (ganeshie8):

do u have options for this ?

OpenStudy (anonymous):

No, I don't that's. all he gave me

OpenStudy (anonymous):

I'm suppose to enter in the letter's from the equations that, given the shape of the graph could be larger then a. I have tried multiple combinations and all of them have been wrong.

OpenStudy (anonymous):

OpenStudy (anonymous):

that is all I have ^

OpenStudy (anonymous):

@ganeshie8 any ideas?

ganeshie8 (ganeshie8):

Now it makes more sense :)

ganeshie8 (ganeshie8):

Notice that all graphs are cutting the positive y axis, that means `p, a, c` will be positive for sure

ganeshie8 (ganeshie8):

since the green graph is rising, `q` also will be positive

ganeshie8 (ganeshie8):

so, overall `p,a,c,q` are positive for sure.

ganeshie8 (ganeshie8):

see if that makes more or less sense...

OpenStudy (anonymous):

wouldn't b and d be positive too, just less then 1?

ganeshie8 (ganeshie8):

very good catch :) yes ! all are positive then ?

OpenStudy (anonymous):

so which are greater then a if all of them are greater then 0?

OpenStudy (anonymous):

I know at least 1 or more of c,d,b,p, and q are less then a

ganeshie8 (ganeshie8):

clearly `c, p` are less than `a`, so eliminate them first

ganeshie8 (ganeshie8):

try `q,b,d`

OpenStudy (anonymous):

how do you know c and p are less then a?

ganeshie8 (ganeshie8):

c, p, a are y-intercepts of graphs right ?

ganeshie8 (ganeshie8):

notice that y-intercepts of blue and green graphs are below the y-intercept of green graph so, c and p are less than a

OpenStudy (anonymous):

oh, okay that makes more sense. He kind of confused me because he gave us this:

OpenStudy (anonymous):

and said that was all we needed to know to do all the homework but never explained anything

ganeshie8 (ganeshie8):

lol thats tricky, but he is true ;) thats all is ever needed if u have 10 hours to work on it trying to figure out ...

OpenStudy (anonymous):

yeah...just looking at the diagram he gave us, its easy to assume that c>a in the homework because g>e in the diagram. he never explained anything about the y axis playing a part

ganeshie8 (ganeshie8):

yes :) C>A because C graph is cutting the y axis a bit higher than the A graph

OpenStudy (anonymous):

I meant c in the homework not in my diagram i drew lol

ganeshie8 (ganeshie8):

ahh okay got u :)

OpenStudy (anonymous):

Do you have any advice on this one as well?

OpenStudy (anonymous):

its really hard to tell because if i click one wrong one or dont click one that's suppose to be clicked its all marked wrong so I can't figure out how to know which ones would be right and which would be wrong

ganeshie8 (ganeshie8):

first start by figuring out the y-intercept of e^x (blue graph)

ganeshie8 (ganeshie8):

y intercept occurs when x = 0, right ?

ganeshie8 (ganeshie8):

so, y intercept of e^x = e^0 = 1

ganeshie8 (ganeshie8):

that means, the value at which the `blue curve` cuts the y axis is `1`

ganeshie8 (ganeshie8):

fien ?

ganeshie8 (ganeshie8):

*fine

OpenStudy (anonymous):

okay, that makes sense

ganeshie8 (ganeshie8):

and since red and green are cutting the y axis at same place, a = b

ganeshie8 (ganeshie8):

and a > 1 and b > 1 also

ganeshie8 (ganeshie8):

so a = 1 is wrong.

ganeshie8 (ganeshie8):

you need to tick ur second option. b > 1 is correct

OpenStudy (anonymous):

what do you mean trick your second option?

ganeshie8 (ganeshie8):

sorry, i meant to select ur second option.

ganeshie8 (ganeshie8):

k > 1 is also correct since the green graph is rising.

OpenStudy (anonymous):

oh okay hah that makes more sense

ganeshie8 (ganeshie8):

that makes the D wrong.

ganeshie8 (ganeshie8):

and since we already know that a = b, option E is also wrong

OpenStudy (anonymous):

and 0<n<1 right?

OpenStudy (anonymous):

because it decays?

ganeshie8 (ganeshie8):

lets go thru the options one by one okay ?

OpenStudy (anonymous):

k

ganeshie8 (ganeshie8):

So far we have : ``` A : false B : true C : true D : false E : false ```

ganeshie8 (ganeshie8):

and ur recent observation on `n` makes the F option wrong

ganeshie8 (ganeshie8):

``` A : false B : true C : true D : false E : false F : false ```

ganeshie8 (ganeshie8):

fine so far ha ?

OpenStudy (anonymous):

yup!

ganeshie8 (ganeshie8):

G is false as we figured out already that b > 1

ganeshie8 (ganeshie8):

H is true

ganeshie8 (ganeshie8):

I is also true

ganeshie8 (ganeshie8):

So : ``` A : false B : true C : true D : false E : false F : false G : false H : true I : true ```

ganeshie8 (ganeshie8):

still fine ?

OpenStudy (anonymous):

yup

ganeshie8 (ganeshie8):

actually the exponent "n" needs to be negative to get a declining graph

OpenStudy (anonymous):

now you lost me..

OpenStudy (anonymous):

I thought it just had to be less then 1 but still greater then 0?

ganeshie8 (ganeshie8):

\(\large y = e^{0.01x}\) is a rising graph

OpenStudy (anonymous):

so that only applies to when the base is 0<base<1?

ganeshie8 (ganeshie8):

http://prntscr.com/3dhcyw

OpenStudy (anonymous):

ok

OpenStudy (anonymous):

so right now we have BCHIK true?

OpenStudy (anonymous):

We were actually wrong, C was false because K had to be less than 1.

ganeshie8 (ganeshie8):

Correct ! k>0 is sufficient

ganeshie8 (ganeshie8):

lets change the answers lol

ganeshie8 (ganeshie8):

we were wrongly thinking k needs to be greater than 1

ganeshie8 (ganeshie8):

and that makes k to be between 0 and 1 so D is true

ganeshie8 (ganeshie8):

try this ``` A : false B : true C : false D : true E : false F : false G : false H : true I : true J : false K : true L : false M : false N : false N : false ```

OpenStudy (anonymous):

Yup! I got those when I figured out c was wrong and plugged them all in and they were correct

ganeshie8 (ganeshie8):

yaay ! nice :)

OpenStudy (anonymous):

Thanks much! :D I'll let you know If I run across anymore that stump me. It's due in an hour so if you don't hear from me by then it means I understood the rest of it :P

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