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SAT Math 3.5 Algebra and Functions 247 Views
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Description:
SAT Math 3.5 Algebra and Functions
Transcript
- 00:04
It's a bird! It's a plane! It's Shmooperman!
- 00:09
If y equals 2x + z over z + 1, what happens to the value of x when y and z are doubled?
- 00:16
And here are the potential answers…
- 00:21
There are three variables, and the question asks what happens to one of them,
- 00:24
x, if we change the other two, y and z.
Full Transcript
- 00:29
Well, first we should isolate x so that we can see what happens.
- 00:32
First, we multiply both sides by z + 1, and get y times z + 1 is equal to 2x + z
- 00:40
Next, we subtract z from both sides so that we can further isolate x.
- 00:44
Finally, we divide both sides by 2, and x is fully isolated.
- 00:49
At this point we can plug in test values.
- 00:52
An easy value is always 1. We can plug in 1 for both y and z.
- 00:56
And we'll see that x is equal to 1/2.
- 01:00
What happens when y and z are doubled?
- 01:02
Well, if we plug in y and z equal 2, we'll get x equals 2 as our answer.
- 01:09
2 is four times bigger than 1/2 and looks like D is our answer. Done.
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