A few more questions ..

S

stef

New member
Joined
Nov 9, 2005
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8
.. then I'm done. I really appreciate the help thus far.

1) Tell whether the two lines are parallel, perpendicular, or neither.

Line I: passes through (4,2) and (-1,3)
Line II: passes through (-2, -7) and (-7, -5)

For line 1 I got a slope of -1/5, for line 2 I got a slope of -2/5.

I said the answer was neither.

Any confirmation on that?


2) Find an equation for the line with the given properties.

Passing thru the point (-4,-1), parallel to the line x -4y = 2

I wrote it in slope-intercept form, such as:

x - 4 . y = 2
-4 . y = -x +2

y = 1/4 x - 1/2

and then on my graph, plotted the points (-4,-1) and (1, 4)

? I have no idea if I did that right. This one confused me badly.

Thanks so much!

Thanks in advance!
 
1) Confirmed.

2) Good job on line 1. For line 2
use
y-y<sub>1</sub> = m(x-x<sub>1</sub>)
y-(-1)=m(x-(-4))
For parallel m = 1/4 (from m of line 1.)
 
I'm lost on the #2 answer you gave.

I appreciate it! I'm just not understanding .. was #2 incorrect?
 
I don't see where you gave the equation for the parallel line (line 2), which I thought was asked for.
 
stef said:
2) Find an equation for the line with the given properties.
Passing thru the point (-4,-1), parallel to the line x -4y = 2
I wrote it in slope-intercept form, such as:
x - 4 . y = 2
-4 . y = -x +2
y = 1/4 x - 1/2
and then on my graph, plotted the points (-4,-1) and (1, 4)
? I have no idea if I did that right. This one confused me badly.
Click to expand...
Stef, you're asked to "find an equation for the line";
BUT you do not show an equation: that's what Gene is telling you.

You're ok down to y = 1/4 x - 1/2; why go to graph next? No need to.
That equation means that that the slope of the new line is 1/4:
parallel lines have the SAME slope.

Now, if you substitute (-4,-1), you get:
-1 = (1/4)(-4) + b (b = y-intercept of new line)
-1 = -1 + b
b = 0 : so new line does not intercept y-axis; it goes through (0,0)

So equation of new line is y = (1/4)x : clear nuff?
 
Where did question (2) come from? That wasn't there when I'd replied.... :shock:

Eliz.
 
stapel: I'm so sorry! I must have been editing my post when you were replying. My bad, I'm new at using these boards but I'll get the hang of it :D

Thanks everybody, it's much clearer now.

I may be back soon to bug you with some questions for my final which is a week from Monday.

Thanks again,

Stef
 
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