Is it true that two lines are parellel when their slopes are the same. Such as, y=4x+7 and y=4x-8? That's true right?
But, what if the slopes are the same,but one is negative? Would they still be parallel?
It's just something I'm confused about- can anyone help me out? Thanks! :)
2007-04-21 05:39:22 · 12 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
no if the one is negative they will not be parallel
the slopes MUST be equal
which means
both must b negative
or both positive
2007-04-21 05:44:57 · answer #1 · answered by Deranged Soul.. 2 · 0⤊ 0⤋
y=4x-8 and y=4x+7 is parellel. But when you flip it around by making it a negative number and the other a positive, on the slope, the will intersect. A way to find out is by graphing. I am sure you know how to graph, but just in case. Remember rise over run. so if you take the equation y=4x-8, then you go down 8 on your graph. Then you take your slope wich is 4. That is also 4 over 1. That is where rise over run comes in. Go up 4 and over 1. Then conect your dots. That is your line. Do the same thing with the other ones and you will see if they are parellel or not. Only if it is a negative you go the other way. I am sure you know all of that but I just thought I would try and help. Good luck!!
2007-04-21 05:52:45 · answer #2 · answered by Anonymous · 0⤊ 0⤋
If the slopes are the same, the lines will be parallel.
If one of the slopes are negative and the other positive, the lines will not be parallel.
If one of the slope is a reciprocal of the other, the lines will be perpendicular.
EX: y = 2x + 4
y = 2x -3 Parallel
y = -2x +7 Not parallel
y = -1/2 x -4 Perpendicular
Hope it helps
2007-04-21 05:48:56 · answer #3 · answered by edward 3 · 1⤊ 0⤋
If the slopes are same in magnitude and sign, they are parallel. Otherwise, they simply arent.
The definition of the slope of a line is the 'tangent function of the angle it makes with the positive direction of the x - axis'.
Consider a line making an angle 'x' with the positive direction of the x - axis. Then ;
The slope, 'm' = tanx.
If the slope of the second line is '-m' ;
-m = -tanx = tan(180-x)
=> If the line with slope 'm' makes an angle 'x' with the positive direction of the x - axis, the line with the positive direction of the x - axis, the line with the slope '-m' makes an angle '(180-x)' with the positive direction of the x - axis, but they are not a pair of parallel lines.
2007-04-21 07:06:16 · answer #4 · answered by shreyas 1 · 0⤊ 0⤋
Slopes that are of opposite sign are not the same. A positive slope rises from lef to right. A negative slope of the same numerical value would rise from left to right. The two lines would eventually intersect.
2007-04-21 05:47:16 · answer #5 · answered by ironduke8159 7 · 0⤊ 0⤋
Yes, it's true. Two lines are parallel when their slopes are same.
If the slopes are same, but one is negative. We can't say they are parallel or not but their directions are opposite to each other.
2007-04-21 05:47:32 · answer #6 · answered by Kapil 3 · 0⤊ 0⤋
No, that's not true. Look at y = x (slope 1)
and y = -x(slope -1). They intersect at the origin.
That means they are not parallel.
2007-04-21 05:46:05 · answer #7 · answered by steiner1745 7 · 0⤊ 1⤋
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2016-12-04 10:11:34 · answer #8 · answered by ? 3 · 0⤊ 0⤋
f(x)= 3x + 2 and
f(x)= -3x - 4
Aren't parallel, as the first one goes upwards and the second one downwards. They would both need to have the same slope for them to be parallel.
The math forum should have an implemented basic graphing utility...
2007-04-21 05:47:22 · answer #9 · answered by Anonymous · 0⤊ 0⤋
no they wouldn't. WHen it says the same it means exactly the same. so one that is negative and one that is positive would intersect
****IN response to "steiner's" answer. they would not be parralel is they intersected.........duh
2007-04-21 05:43:07 · answer #10 · answered by Brandon 3 · 1⤊ 0⤋