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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
 one year ago
 one year ago
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
 one year ago
 one year ago

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tjones89Best 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?
 one year ago

rebelchick777Best ResponseYou've already chosen the best response.0
yeah,but how do i write them as function rules?
 one year ago

tjones89Best 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
 one year ago

rebelchick777Best ResponseYou've already chosen the best response.0
my teacher told me to write the functions as f(x)=...
 one year ago

tjones89Best 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
 one year ago

rebelchick777Best ResponseYou've already chosen the best response.0
ok so then for the second one would it be... f(x)=$15x
 one year ago

tjones89Best ResponseYou've already chosen the best response.0
but actually I made a mistake on the first one
 one year ago

rebelchick777Best ResponseYou've already chosen the best response.0
I d dont understand how to write the third one though.
 one year ago

tjones89Best 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
 one year ago

tjones89Best ResponseYou've already chosen the best response.0
so you just convert 3.8 cents into dollars which should be .038
 one year ago

rebelchick777Best ResponseYou've already chosen the best response.0
the profit you make selling flowers at $1.50 each when each flower costs you $.80
 one year ago

tjones89Best ResponseYou've already chosen the best response.0
what is the profit if I sell one flower?
 one year ago

tjones89Best ResponseYou've already chosen the best response.0
right.. and if i sell two flowers?
 one year ago

rebelchick777Best ResponseYou've already chosen the best response.0
a dollar and 40 cents
 one year ago

tjones89Best 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
 one year ago

rebelchick777Best ResponseYou've already chosen the best response.0
ok so... would the function be f(x)=.70x?
 one year ago

rebelchick777Best 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?
 one year ago

tjones89Best 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
 one year ago

tjones89Best 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?
 one year ago

rebelchick777Best ResponseYou've already chosen the best response.0
yeah. i was wondering where you d plug in the $10.
 one year ago

tjones89Best ResponseYou've already chosen the best response.0
the ten dollars goes where dollars is represented in the equation
 one year ago

tjones89Best 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
 one year ago

tjones89Best 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
 one year ago

tjones89Best ResponseYou've already chosen the best response.0
does that make sense?
 one year ago

rebelchick777Best ResponseYou've already chosen the best response.0
16.95lb. is what i got. Yeah it does make sense.
 one year ago

rebelchick777Best ResponseYou've already chosen the best response.0
dw:1350441039671:dw
 one year ago

rebelchick777Best ResponseYou've already chosen the best response.0
dw:1350441111447:dw
 one year ago

rebelchick777Best 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.
 one year ago

tjones89Best 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)
 one year ago

rebelchick777Best ResponseYou've already chosen the best response.0
i know that,but idk what number it should be.,
 one year ago

tjones89Best 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
 one year ago

tjones89Best ResponseYou've already chosen the best response.0
with m = (y2y1)/(x2x1)
 one year ago

rebelchick777Best ResponseYou've already chosen the best response.0
ok. so what should i get?
 one year ago

tjones89Best ResponseYou've already chosen the best response.0
lets use the points: (0,1) and (1,3) m = (31)/(10) = 2
 one year ago

rebelchick777Best 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.
 one year ago

tjones89Best ResponseYou've already chosen the best response.0
maybe graphing the points and seeing them line up would help
 one year ago

rebelchick777Best ResponseYou've already chosen the best response.0
the y's are going up by two except for the last one.
 one year ago

tjones89Best 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
 one year ago

tjones89Best ResponseYou've already chosen the best response.0
dw:1350442466454:dw
 one year ago

tjones89Best ResponseYou've already chosen the best response.0
thats the pattern if we follow the negative x points
 one year ago

tjones89Best 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
 one year ago

tjones89Best ResponseYou've already chosen the best response.0
whereas the second one was just y = mx
 one year ago

rebelchick777Best ResponseYou've already chosen the best response.0
ok so whats the function rule.
 one year ago

tjones89Best 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
 one year ago

tjones89Best 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
 one year ago

tjones89Best 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
 one year ago

tjones89Best ResponseYou've already chosen the best response.0
so now that we know b, we can finally write the function as y = 2x 1
 one year ago
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