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Mathematics 7 Online
OpenStudy (anonymous):

A line contains the points (3, -4) and (5, 2). Another line graphed in the same coordinate plane contains the points (0, -2) and (6, -4). Based on the slopes of these lines are they parallel, perpendicular or neither?

OpenStudy (anonymous):

can someone please help ?

OpenStudy (e.mccormick):

OK, did you find the equations of the lines?

OpenStudy (anonymous):

i think so

OpenStudy (e.mccormick):

What did you get?

OpenStudy (anonymous):

the first one i got 1 and the second set of numbers i got -10 over 6

OpenStudy (e.mccormick):

How did you get those? Something is not right there and I want to see if we can find out where the mistake is.

OpenStudy (anonymous):

i did 2-3 over 5-4 for the first set and -4-6 over 6-0 . the first set gave me -1 over 1 which goes to 1 and the second set i got -10 over 6

OpenStudy (e.mccormick):

Ah, you confused which values go where. OK. Let me show you something about that.

OpenStudy (e.mccormick):

Usually you go through a section where you have the slope formula: \[m=\frac{\Delta y}{\Delta x}\implies m=\frac{y_1-y_2}{x_1-x_2}\] It really does not matter which point you choose as \((x_1,y_1)\) or \((x_2,y_2)\), but once one is chosen as being first, you must use the numbers from it in the first spots. So lets take your points, \((3,-4)\) and \((5,2)\). If I say \((5,2)\) is the first one, then I must use this to get the slope:\[m=\frac{2-(-4)}{5-3}\]

OpenStudy (anonymous):

have sent me something else

OpenStudy (anonymous):

oh okay thank you

OpenStudy (e.mccormick):

Yah, I was writing it up in an editor to make sure I for it all right. Causes a delay, but helps me make sure I get you good, clear info.

OpenStudy (anonymous):

oh okay

OpenStudy (anonymous):

would i do the same for the second set of numbers

OpenStudy (e.mccormick):

Yes.

OpenStudy (e.mccormick):

Once you have the two m values, let me know what you got.

OpenStudy (anonymous):

i got the first m value is 3 and the second m value is -1

OpenStudy (e.mccormick):

The first is 3. But check that second one. What did numbers did you put where in the slope formula?

OpenStudy (anonymous):

-4 -2 over 6-0

OpenStudy (e.mccormick):

AH! -4 - (-2)

OpenStudy (e.mccormick):

Sign is like pants! Be careful not to drop them in the wrong place or it can be embarrassing. Hehe.

OpenStudy (e.mccormick):

\[\frac{-4-(-2)}{6-0}\implies \frac{-4+2}{6}\] That help?

OpenStudy (anonymous):

would m be one third

OpenStudy (e.mccormick):

Negative one third.

OpenStudy (anonymous):

oh okay

OpenStudy (e.mccormick):

That means you have \(m_1=3\) and \(m_2=-\frac{1}{3}\) To be honest, slope is one of the ones I regularly make mistakes on. Because the y is on top and I keep wanting to put the x there. It means I have to be very careful when I do slopes! Now, do you know the rules for parallel, perpendicular, and other lines as it relates to slope? The value of \(m_1\) and \(m_2\) tells you about the relationship of the lines.

OpenStudy (anonymous):

it wouldn't be paralleled or perpendicular cause they don't equal the same or would they intersect

OpenStudy (e.mccormick):

Well, they are either parallel or they intersect. How would you tell if they were parallel?

OpenStudy (e.mccormick):

Three choices for two lines: Parallel Intersect, but not at right angles Intersect at right angles, AKA Perpendicular

OpenStudy (anonymous):

if they were parallel then they wouldn't intersect

OpenStudy (e.mccormick):

Yes, but do you know what that would mean in terms of the slope? That is the final part of this question, what the slope means. They are either Parallel OR They do Intersect, but not at right angles OR They do Intersect at right angles, AKA Perpendicular It must be one of those three and the slope tells us which. Do you know how or do you need help with that part?

OpenStudy (anonymous):

do you mind helping me with that part also

OpenStudy (e.mccormick):

It is no problem! |dw:1367460480610:dw| These are the three choices, basically. Agreed?

OpenStudy (anonymous):

yes

OpenStudy (e.mccormick):

In Parallel, the slope is the same! |dw:1367460570740:dw|

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