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SAT Math 3.5 Algebra and Functions 247 Views


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SAT Math 3.5 Algebra and Functions

Language:
English Language

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.

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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