Maths *updated*

[ImagineDragons]

So I figured out how to do 1-6, but how do I do these?


7. Evaluate the function below over the domain {-1, 0,
1, 2}. As the values of the domain increase, do the
values of the function increase or decrease?

y = (3/4)ˣ

8. Suppose an investment of $5,000 doubles every 12
years. How much is the investment worth after 36
years? After 48 years?
Write and solve an exponential equation.

9. Does the function represent exponential growth or
exponential decay? Identify the growth or decay
factor.

= 9 ∙ (1/2)ˣ

10. You deposit $520 in an account with 4% interest
compounded monthly. What is the balance in the
account after 5 years?

[fiction-factory]

Q8. Think- what will the $5000 be worth after 12 years. Answer $10000. It will double in value again to $20000 after another 12 years (i.e. after 24 years). I'll leave you to finish it off.

[fiction-factory]

y = (3/4)ˣ
put x = -1 The function becomes 4/3
put x= 0. Function becomes 1
put x =1. Function = 3/4
put x=2. Function = 9/16.
as x increases beyond 2 the value of the function reduces closer to zero

[Kidas]

The first one talking about the domain is a fancy-schmancy way of asking what the value of y is when x= -1 and 0 and 1 and 2.

Remove the strange wording and you should be able to get the answer quite easily - especially if you have done the earlier set you asked about

[fiction-factory]

I'll leave some for you

[Kidas]

OK, FF think we crossed - I'll leave it to you to do the tutoring

[Kidas]

Q9: is the function growing or decaying... Easy, really.

Q10: I find a spreadsheet helps enormously when trying to work this kind of calculation.

[Peter Pedant]

9 - plug in a few values as done with the other questions
and does the function increase or decrease ?

to start - 0 it is 9 , 1 it is 4.5 .... do the rest

use the fact that exponentials dont have a turning point to conclude that once it is has started, it will go on

10 - this is not 4% monthly is it - 48% per year
5 x 12 is 60 so you use the compound interest formula to the power 60.
your only decision is whether the interest rate is 4/100 or 4/1200

[Peter Pedant]

excel is fun on you tube
does quite a good basic maff and business viddies
M Girvin does a LOT of this stuff

10 as Kidas says is grist to a spreadsheet mill

[fiction-factory]

Can you just check please I-D that question 10 has been typed correctly. Is it 4% per month? or 4% pa but credited monthly? or something else?

[ImagineDragons]

Wait how did you do 10 again?

[fiction-factory]

I'm not sure Q9 is typed correctly either, although i note this is the same as when you asked before.
You say the function is 9 ∙ (1/2)ˣ
I can see the right hand bit says (1/2) to the power x but I'm not sure what the left hand bit (the "9 ∙ ")- does the whole thing mean 9 x (1/2)ˣ ?

[ImagineDragons]

yeah thats what im struggling with on 10

[ImagineDragons]

and yeah the dot i meant the multiplication sign

[fiction-factory]

Thanks. That was what PP assumed too so I thought it would be that

[fiction-factory]

On 10 If the 4% figure was the monthly interest rate the value of your $520 investment after 5 years would be just under $5470. Not a bad return!