[Script Info]
Title: 
[Events]
Format: Layer, Start, End, Style, Name, MarginL, MarginR, MarginV, Effect, Text
Dialogue: 0,0:00:00.54,0:00:02.31,Default,,0000,0000,0000,,- [Instructor] We're told the\Nsystem of linear equations
Dialogue: 0,0:00:02.31,0:00:04.41,Default,,0000,0000,0000,,below is graphed on the coordinate grid.
Dialogue: 0,0:00:04.41,0:00:06.36,Default,,0000,0000,0000,,Okay, we see that.
Dialogue: 0,0:00:06.36,0:00:08.52,Default,,0000,0000,0000,,Then, it says: What is the value
Dialogue: 0,0:00:08.52,0:00:11.28,Default,,0000,0000,0000,,of y equals -x - 7
Dialogue: 0,0:00:11.28,0:00:13.35,Default,,0000,0000,0000,,when x is equal to -8.
Dialogue: 0,0:00:13.35,0:00:15.90,Default,,0000,0000,0000,,So the graph y equals -x - 7,
Dialogue: 0,0:00:15.90,0:00:17.91,Default,,0000,0000,0000,,that's this blue line here,
Dialogue: 0,0:00:17.91,0:00:19.02,Default,,0000,0000,0000,,and they tell us, right?
Dialogue: 0,0:00:19.02,0:00:22.47,Default,,0000,0000,0000,,That the point -8, 1 is on that line.
Dialogue: 0,0:00:22.47,0:00:24.54,Default,,0000,0000,0000,,So when x is equal to -8,
Dialogue: 0,0:00:24.54,0:00:26.13,Default,,0000,0000,0000,,y is equal to 1.
Dialogue: 0,0:00:26.13,0:00:27.75,Default,,0000,0000,0000,,So we could type that in.
Dialogue: 0,0:00:27.75,0:00:30.42,Default,,0000,0000,0000,,And then, they ask us:
Dialogue: 0,0:00:30.42,0:00:34.86,Default,,0000,0000,0000,,What is the y-value of the bronze line
Dialogue: 0,0:00:34.86,0:00:35.91,Default,,0000,0000,0000,,or the brown line here,
Dialogue: 0,0:00:35.91,0:00:37.89,Default,,0000,0000,0000,,y is equal to 1/2x - 1
Dialogue: 0,0:00:37.89,0:00:39.57,Default,,0000,0000,0000,,when x is equal to -8.
Dialogue: 0,0:00:39.57,0:00:40.98,Default,,0000,0000,0000,,So we don't even have to compute it.
Dialogue: 0,0:00:40.98,0:00:43.35,Default,,0000,0000,0000,,We see when x is equal to -8,
Dialogue: 0,0:00:43.35,0:00:45.32,Default,,0000,0000,0000,,we get y is equal to -5,
Dialogue: 0,0:00:45.32,0:00:47.85,Default,,0000,0000,0000,,so we put -5 there.
Dialogue: 0,0:00:47.85,0:00:49.50,Default,,0000,0000,0000,,And then, they say:
Dialogue: 0,0:00:49.50,0:00:52.50,Default,,0000,0000,0000,,Is x equal -8 a solution?
Dialogue: 0,0:00:52.50,0:00:55.86,Default,,0000,0000,0000,,Well, the only way that x\Nequals -8 would be a solution
Dialogue: 0,0:00:55.86,0:00:58.47,Default,,0000,0000,0000,,is if the y value of those lines
Dialogue: 0,0:00:58.47,0:01:00.66,Default,,0000,0000,0000,,when x equals -8 were the same,
Dialogue: 0,0:01:00.66,0:01:01.68,Default,,0000,0000,0000,,but they're clearly not.
Dialogue: 0,0:01:01.68,0:01:02.97,Default,,0000,0000,0000,,And in fact, we would see it visually.
Dialogue: 0,0:01:02.97,0:01:03.99,Default,,0000,0000,0000,,If it was a solution,
Dialogue: 0,0:01:03.99,0:01:06.63,Default,,0000,0000,0000,,the two lines would intersect\Nat that point but they don't.
Dialogue: 0,0:01:06.63,0:01:08.01,Default,,0000,0000,0000,,There's actually two\Ndifferent points here.
Dialogue: 0,0:01:08.01,0:01:09.60,Default,,0000,0000,0000,,They don't overlap.
Dialogue: 0,0:01:09.60,0:01:12.87,Default,,0000,0000,0000,,So this is not a solution
Dialogue: 0,0:01:12.87,0:01:13.70,Default,,0000,0000,0000,,and we're done.