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#1 2006-01-28 09:05:00
- ineedhelp
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- Registered: 2006-01-21
- Posts: 7
check my homework
I have two homework problems that I'm not sure I got right. If someone could tell me if my answer is correct that would be great. If its not right, i'll try to solve it again.
Suppose the sales of a particular brand of appliance satisfy the relationship: S(x) = 140x + 100 where S(x) represents the number of sales in year x, with x = 0 corresponding to 1982. Find the number of sales in 1987.
S(x) = 140(5) + 100
I came up with Sales in 1987 were 800.
Decide whether the pair of lines is parallel, perpendicular, or neither: the line through (3, -5) and (-1, 7) and the line through the points (6, -13) and (-2,11)
The first line slope is 2/2 and and the second line slope is -2/4. I came up with neither, because the the slope would be the same if parallel or reciprocal if perpendicular. In this case they are niether.
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#2 2006-01-28 09:50:46
- mathsyperson
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- Registered: 2005-06-22
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Re: check my homework
The first answer is fine.
In the second one, the gradients need to be calculated differently.
Between (3, -5) and (-1, 7), there is a gradient of
Similarly, between (6, -13) and (-2, 11), there is a gradient of
They have the same gradient and so are parallel.
Why did the vector cross the road?
It wanted to be normal.
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#3 2006-01-28 10:23:39
- MathsIsFun
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Re: check my homework
And the computer can give you a little help with the straight line graph calculator
"The physicists defer only to mathematicians, and the mathematicians defer only to God ..." - Leon M. Lederman
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#4 2006-01-28 11:05:32
- mikau
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- Registered: 2005-08-22
- Posts: 1,504
Re: check my homework
What the heck is gradients? Oddly my mathbook never mentioned that term.
A logarithm is just a misspelled algorithm.
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#5 2006-01-28 11:29:12
- ineedhelp
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- Registered: 2006-01-21
- Posts: 7
Re: check my homework
The first answer is fine.
In the second one, the gradients need to be calculated differently.
Between (3, -5) and (-1, 7), there is a gradient of
Similarly, between (6, -13) and (-2, 11), there is a gradient of
They have the same gradient and so are parallel.
I see my mistake. I did 7-5 and -1+3 to get 2/2 and 11-13 and -2+6 to get -2/4. I'll fix it. Thanks.
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#6 2006-01-28 11:55:16
- mathsyperson
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- Registered: 2005-06-22
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Re: check my homework
What the heck is gradients? Oddly my mathbook never mentioned that term.
A gradient is just the slope of a line. Well, it's actually the slope of a curve at a given point, but it's most commonly applied to lines. It's basically an less technical way of saying dy/dx.
Why did the vector cross the road?
It wanted to be normal.
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