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rebelchick777
Group Title
I need some help please. Write a function rule to describe each statement...
the cost in dollars of printing dollar bills when it costs 3.8cents to print a dollar bill.
the amount of money you earn mowing lawns at $15 per lawn.
the profit you make selling flowers at $1.50 each when each flower costs you $.80
 2 years ago
 2 years ago
rebelchick777 Group Title
I need some help please. Write a function rule to describe each statement... the cost in dollars of printing dollar bills when it costs 3.8cents to print a dollar bill. the amount of money you earn mowing lawns at $15 per lawn. the profit you make selling flowers at $1.50 each when each flower costs you $.80
 2 years ago
 2 years ago

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tjones89 Group TitleBest ResponseYou've already chosen the best response.0
it costs 3.8 cents to print 1 dollar its costs 2 times 3.8 cents to print two dollars it costs 3 times 3.8 cents to print 3 dollars you can see a pattern here right?
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
yeah,but how do i write them as function rules?
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
we use variables! there should be two of them; one will represent the number of dollars, lets call that x and the other will represent the cost to print them, lets call that y
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
my teacher told me to write the functions as f(x)=...
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
ok lets use f(x) instead of y so the cost to print, f(x), should equal the number of dollars, x, times 3.8 cents
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
so f(x)=3.8x
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
ok so then for the second one would it be... f(x)=$15x
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
but actually I made a mistake on the first one
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
I d dont understand how to write the third one though.
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
the function for the first part should give us the cost in dollars, with f(x) = 3.8x we'll end up with the number of cents
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
so you just convert 3.8 cents into dollars which should be .038
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
the profit you make selling flowers at $1.50 each when each flower costs you $.80
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
what is the profit if I sell one flower?
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
70 cents
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
right.. and if i sell two flowers?
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
a dollar and 40 cents
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
which is the same as 2 times 70 cents right? if I sell 3 flowers the profit would be 3 times 70 cents and if I sell x flowers the profit will be x times 70 cents
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
ok so... would the function be f(x)=.70x?
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
yes! good job
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
Thanks. Now i have another question i have this equation... f(x)=$0.59x where x+number of pounds. if i had $10 to buy that turkey how big a turkey could i buy?
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
you have f(x) = $0.59x which in words is, the cost of a turkey, f(x), is the number of pounds, x, times 59 cents
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
so the cost of a turkey is a function of the number of pounds that it weighs, does that make sense so far?
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
yeah. i was wondering where you d plug in the $10.
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
the ten dollars goes where dollars is represented in the equation
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
x is pounds f(x) is dollars so the equation, when we put in 10 dollars, becomes $10 = $0.59x
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
and by solving for x you will have found out how big a turkey you could by with 10 dollars
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
does that make sense?
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
16.95lb. is what i got. Yeah it does make sense.
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
dw:1350441039671:dw
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
dw:1350441111447:dw
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
i dont see the rule for either of these. It says to write a function rule. By the way.. they are two seperate questions.
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
ok lets start with the top one we need to find a way to relate x and y in other words we need to be able to describe how much y changes when x changes we can do this with a function y = x times (some number)
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
i know that,but idk what number it should be.,
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
we can find out what number it is by calculating the slope between the points that are given
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
with m = (y2y1)/(x2x1)
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
ok. so what should i get?
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
lets use the points: (0,1) and (1,3) m = (31)/(10) = 2
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
i understand it for the second table the answer would be f(x)=4.5x. But i still dont see a pattern in the first one.
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
maybe graphing the points and seeing them line up would help
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
the y's are going up by two except for the last one.
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
because its a negative x in the last one, if it were positive 3 then y would be 7
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
dw:1350442466454:dw
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
thats the pattern if we follow the negative x points
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
the reason it isnt as easy to see as the second problem is because this function will have the form y = mx + b
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
whereas the second one was just y = mx
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
ok so whats the function rule.
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
well we're using y = mx + b as the template for our function, we found m to be 2, now we need to find b
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
so we have y = 2x + b since we're given points we can substitute one in for the values of x and y, and then solve for b so if we use (0,1) as our point we get 1 = 2(0) + b so b = 1
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
and keep in mind that we could have used any of the points that were given for example if we used (2,5) we get 5 = 2(2) +b and again b = 1
 2 years ago

tjones89 Group TitleBest ResponseYou've already chosen the best response.0
so now that we know b, we can finally write the function as y = 2x 1
 2 years ago

rebelchick777 Group TitleBest ResponseYou've already chosen the best response.0
thank you.
 2 years ago
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