# Tutor.com Linear Functions Session

##### Sep. 30, 2013

Session Transcript - MTH/208 - MTH/208, 9/23/2013 3:09PM - Tutor.comSession Date: 9/23/2013 3:09PM
Length: 15.3 minute(s)
Subject: MTH/208 - MTH/208

System Message
[00:00:00] *** Please note: All sessions are recorded for quality control. ***

[00:00:00] write and equation in slope-intercept form of the line satisfying the given conditions the line passes through (2,-7) and is parallel to the line whose equation is y=2x+3 type the slope intercept form of the equation of the line

John G (Tutor)
[00:00:10] Hello, hello! Welcome to tutor.com !

[00:00:33] ok i need help on this one i more or less have an idea but dont know if it is correct

John G (Tutor)
[00:00:56] Okay sounds good. Why don't you go ahead and tell me your idea, and we'll start from there.

[00:01:24] first the two points 2 is x1 & - 7 is y2
[00:01:47] so using the formula y=mx+b
[00:02:38] i sub the y for -7 and the mx should have 2 (2) + 3 right
[00:03:54] is this correct

John G (Tutor)
[00:04:18] Okay now I see. so that's not exactly what we'll want to do, but you're definitely on the right track

[00:04:31] ok

John G (Tutor)
[00:04:33] So let me ask you this, is there any way to tell what the slope of our line is going to be?

[00:04:51] it is the 2

John G (Tutor)
[00:05:13] Right, perfect. And we know that because we're parallel to the line y = 2x+3. For two lines to be parallel, the slope has to be the same
[00:05:33] So now we need to find our b
[00:05:48] because b (y-intercept) is going to be different for the line going through the point it gives us.

[00:06:14] so b is not the 3

John G (Tutor)
[00:06:36] nope, it sure isn't. That's the b it gives for our reference line. But our new line has to have a b all of its own.

[00:06:48] k

John G (Tutor)
[00:07:02] Remember, parallel lines have the same slope (m) but not the same y-intercept( b)
[00:07:14] so how can we find b for our line?

[00:07:26] i dont know

John G (Tutor)
[00:07:42] okay so let's take a look at our y = mx +b
[00:07:44] we know y
[00:07:45] and x
[00:07:54] we also know m
[00:08:10] So let's plug those values in and solve for b.

[00:08:42] ok so it is -7=2x+b

John G (Tutor)
[00:08:55] okay close, but don't forget to also plug in 2 for x

[00:09:54] ok so that is -7=4+b

John G (Tutor)
[00:10:00] yep perfect
[00:10:06] and what does that give us for b?

[00:10:47] do we need to do another steop here, dont i need to subtract -4 from each side

John G (Tutor)
[00:10:59] yep, very good. subtract 4 from each side

[00:11:13] -11

John G (Tutor)
[00:11:27] awesome!
[00:11:41] Alright, do we have all the information we need now to write the equation for our line?

[00:11:47] ok
[00:12:24] do we use y=mx+b

John G (Tutor)
[00:12:30] yep, we sure do.
[00:12:37] and we'll want to plug in our values for m and b.

[00:13:23] so it is -7=2x-11

John G (Tutor)
[00:13:49] Okay close.. But don't forget that although we used -7 to find our y-intercept, we don't want -7 in our general equation for the line
[00:13:53] We just want a y there

[00:14:21] ok so y=2x-11

John G (Tutor)
[00:14:27] yep, perfect!
[00:14:28] Good job.