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SAT Math 3.4 Algebra and Functions 239 Views


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Description:

SAT Math 3.4 Algebra and Functions

Language:
English Language

Transcript

00:02

Put this in your calculator and shmoop it...

00:05

2 xy + 2 = 1 over x + y.

00:09

Solve for y in terms of x.

00:11

And here are the potential answers...

00:18

It's important to remember that when a question asks us to solve for something in terms of

00:21

something else, it's just asking us to isolate the variable.

00:27

So let's get started. We need to isolate y.

00:30

We can do this by putting all the terms with y's on one side first.

00:34

We subtract y from both sides, and 2 from both sides.

00:38

Next, we'll factor out the y on the left side of the equation, and we're left with y times

00:42

the quantity 2x - 1 is equal to 1/x - 2.

00:47

Then, we divide both sides by 2x - 1, so our y is isolated.

00:52

We can factor out 1/x from the top half of the right side,

00:56

and we'll be left with (1/x)(1 - 2x) on top.

01:02

Now, the top has 1 - 2x, and the bottom has 2x - 1.

01:06

Well look at them closely...they're just negatives of each other.

01:09

So, we can rewrite the bottom as -1 times 1 - 2x

01:15

We can clearly see that 1 - 2x can be cancelled out.

01:18

We're left with y = -1/x.

01:23

So our answer is (A).

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