linear equations of gas prices  TOPIC_SOLVED

Quadratic equations and inequalities, variation equations, function notation, systems of equations, etc.

linear equations of gas prices

Postby jonesbetty on Tue Nov 08, 2011 8:57 pm

1) the linear equation y=0.15x+0.79 represents an estimate of the average cost of gas for year x starting in 1997. The year 1997 would be represented by x=1, for example, because it is the first year in the study. Similarly, 2005 would be year 9 or x=9
a)what year would be represented by x=4
b) what x-value represents the year 2018
c) what is the slope or rate of change of this equation
d) what is the y-intercept
e)what does the y-intercept represent
f) assuming this growth trend continues, what will the price of gasoline be in the year 2010? How did you arrive at your answer

2) the line y=0.15x+0.79 represents an estimate of the average cost of gasoline each year. The line 0.11x-y=-0.85 estimates the price of gasoline in January of each year.
a) do you expect the lines to be intersecting, parallel, or perpendicular? explain your reasoning
b) use the equations of the lines to determine if they are parallel. What did you find?
c) did your answer to part b confirm your expectation in part a?
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Re: linear equations of gas prices  TOPIC_SOLVED

Postby maggiemagnet on Wed Nov 09, 2011 12:04 pm

jonesbetty wrote:1) the linear equation y=0.15x+0.79 represents an estimate of the average cost of gas for year x starting in 1997. The year 1997 would be represented by x=1, for example, because it is the first year in the study. Similarly, 2005 would be year 9 or x=9
a)what year would be represented by x=4

Use what they explained in the last two sentences of the exercise.

jonesbetty wrote:b) what x-value represents the year 2018

Use the same bit to answer this part, too.

jonesbetty wrote:c) what is the slope or rate of change of this equation

Look at the slope-intercept equation they gave you, and copy down the slope value.

jonesbetty wrote:d) what is the y-intercept

Look at the slope-intercept equation they gave you, and copy down the intercept value.

jonesbetty wrote:e)what does the y-intercept represent

Try this lesson, if you're not sure.

jonesbetty wrote:f) assuming this growth trend continues, what will the price of gasoline be in the year 2010? How did you arrive at your answer

Find the x-value for "2010" using the method you used for (a) and (b). Plug this in and simplify.

jonesbetty wrote:2) the line y=0.15x+0.79 represents an estimate of the average cost of gasoline each year. The line 0.11x-y=-0.85 estimates the price of gasoline in January of each year.
a) do you expect the lines to be intersecting, parallel, or perpendicular? explain your reasoning

Think about what you know about slopes and graphing to answer this part.

jonesbetty wrote:b) use the equations of the lines to determine if they are parallel. What did you find?
c) did your answer to part b confirm your expectation in part a?

What did you "find"? What did this tell you?
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