college algebra..2 problems help?

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momina4468

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Sep 2, 2008
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The problem reads:
Write an equation of the line satisfying the given conditions. Put the final answer in the form y= mx+b.
1. Through (5,0) and (5, -3)
**** would the answer be x= 5 or undefined since the slope is - 10/0= undefined???

Also...

2. If A= 65+1.7t and B= 26+4.1t represent the population (in millions) of two countries, A and B, then in what year will the population of country A be equal to that of county B?

***** I got 16th year....is this correct?
 
Are you sure the points are (5, 0) and (5, -3)?

x = 5 is the equation for this VERTICAL line, but there is no way to write x = 5 in the form y = mx + b.

Either you've been given sloppy instructions, or your coordinates are not correct.

On the second problem, 16 years is correct, but it is only correct IF you are allowed to round your result to the nearest year AND if the time unit for t is "years" (you didn't say).

~ Mark
 
I am so sorry about the first problem ....the two points were (5,7) and (5,-3)

but for the second problem that is honestly all that the problem states :$
 
momina4468 said:
I am so sorry about the first problem ....the two points were (5,7) and (5,-3)

but for the second problem that is honestly all that the problem states :$
Click to expand...

Will you please show us how you calculated the slope to be 10/0? I think you're probably mixing up your x-coordinates and y-coordinates in the formula for slope.

On the second problem, if I read the question as "Within what year from now will the populations be equal?, then the answer "Within the 16th year" seems good to me.

~ Mark :)
 
momina4468 said:
m= (y2-y1)/(x2-x1)
m= (-3-7)/(5-5)
m= -10/0 Right? or am I still wrong?
Click to expand...

Yes, this is what I wanted to see. You are correct.

Your teacher is sloppy if your teacher thinks that x = 5 is some form of y = mx + b.

Anyway, x = 5 is the correct equation for the line through those two points.
 
momina4468 said:
The problem reads:

2. If A= 65+1.7t and B= 26+4.1t represent the population (in millions) of two countries, A and B, then in what year will the population of country A be equal to that of county B?

***** I got 16th year....is this correct?
Click to expand...

You should be able to check this yourself (generally problem with "solve" can be checked for correctness - easily).

make chart:

Code: 
                     Population
Year              A              B

15               90.5          87.5
16               92.2          91.6
17               93.9          95.7

Now you decide whether you are right or wrong!

You could also "graphically" solved these two equations and looked at the point of intersection (easily done with graphic-calculator)
 
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