The price of products may increase due to inflation and decrease due to depreciation. Derek is studying the change in the price of two products, A and B, over time. The price f(x), in dollars, of product A after x years is represented by the function below: f(x) = 72(1.25)x Part A: Is the price of product A increasing or decreasing and by what percentage per year? Justify your answer. (5 points) Part B: The table below shows the price f(t), in dollars, of product B after t years: t (number of years) 1 2 3 4 f(t) (price in dollars) 65 84.5 109.85 142.81 Which product recorded a greater percentage change in price over the previous year? Justify your answer. (5 points)
About A. If you're multiplying two positive numbers, what do you think you're doing- increasing or decreasing?
@jim_thompson5910 ???can you help me? please
i really need help,guyss
Your increasing because when you multiply 2 positive numbers you increase
You increased when multiplying 2x2. Mai name is the answar
@Michele_Laino @Vocaloid ???
the general form of a growth/decay exponential function is f(x) = a(r)^x our function is f(x) = 72(1.25)^x can you tell me what r = ?
i dont know, :(
f(x) = a(r)^x f(x) = 72(1.25)^x r = ?
look at the underlined parts can you tell me what r = ?
right, r = 1.25 the value of r tells us whether the function is increasing or decreasing if r > 1, our function is increasing if r < 1, our function is decreasing is our function increasing or decreasing?
right, increasing now we need to find the percentage if r = 1.25 = 1 + (percentage/100), what is our percentage?
r = 1.25 = 1? @Vocaloid
i dont know @Vocaloid :(
not quite, perhaps we work it out a bit differently 1.25 = 1 + __ fill in the blank
this its what i get 1.25
not quite what number do I have to add to 1 to get 1.25?
72(1.25)? sorry but im not good at math @Vocaloid :(
1.25 - 1 = ?
right, 0.25 is the number I was trying to get at earlier, haha 0.25 (which is also equal to 25%) represents the percent increase per year
so we're finished with part A, ready to move to part B?
so wait the answer for part A? its
0.25 (which is also equal to 25%) represents the percent increase per year?
please read what part A is asking and review what we have done so far
"Part A: is the price of product A increasing or decreasing and by what percentage per year?"
right, and what percentage?
right now are you ready to move to part B?
alright, to find the percent increase for part B, we need to calculate the ratio f(2)/f(1) looking at the table, we know that f(2) = 84.5 f(1) = 64 f(2)/f(1) = ?
o no wait
o yes its 2? right?
|dw:1437185687149:dw| try one more time
oh, whoops, typo on my part |dw:1437185910222:dw|
can you try again, using 65 instead of 64?
65/64? thats what u say?
that's not what I meant, please look at this diagram |dw:1437186028756:dw|
right! this gives our r value, 1.3 so, r = 1.3 now we need to find the percent increase 1.3 = 1 + (increase) what is the value of (increase)?
yes! so, our increase is 0.3, which is the same as 30%
its that a question?
we need it to solve the last question
we found the percent increase for product A and product B, now tell me which one is bigger
1.3? right? @Vocaloid ?
so whats nexts?
which product had the bigger increase? A or B?
please read over what we did carefully...
also, please read the problem again
O sorry my bad
its B SORRY
SO we done?
for make sure i writte correct the answer its:
Part A: the price of product is increasing 25%Part Part B: 1.3
i writte correct
... please read what part B is asking
"Part B: Which product recorded a greater percent change in price over the previous year?"
B? 0.3? :/
it's asking which product (product A or product B) had the greater percent change
ITS product B? RIGHT
SO thats the answer for part B