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Functions Videos 43 videos

Piecewise Functions
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Don’t even think about starting up your combo lemonade/fro-yo stand without first making sure you understand piecewise functions. You’re just a...

Domain and Range
5384 Views

Domain and range: two terms you will learn to love (or hate with a vengeance). The domain is the set of all possible x values, and range is the set...

Functions as Models
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Functions briefly flirted with the idea of being infomercial hosts, but they didn’t shine when talking on-camera. They’re much better off in th...

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SAT Math 3.1 Algebra and Functions 250 Views


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Description:

SAT Math 3.1 Algebra and Functions

Language:
English Language

Transcript

00:03

Here’s your shmoop du jour, brought to you by Real Numbers.

00:06

Seriously – they haven’t had any plastic surgery whatsoever.

00:10

G of x equals the square root of 4 minus x squared.

00:14

For which values of x is the equation true? 

00:17

And here are the potential answers…

00:20

Ok, so the question tells us we’re trying to find the values of x that make this square root function true.

00:27

Well, we know that since g of x involves a radical,

00:30

the only way this equation is true is if the stuff under the radical is non-negative.

00:37

Which…is just a fancy-shmancy way of saying zero or higher.

00:41

For this to happen, x squared can't be greater than 4.

00:44

In other words, x squared must be less than or equal to 4.

00:49

We can automatically eliminate answer choice E as “all real numbers”

00:52

To put this equation another way, x must be equal to or fall between -2 and 2.

00:59

Let’s try a number just to see if this works…

01:02

we’ll go with the ever popular zero. 4 minus 0 squared, or 4 minus 0, is 4.

01:08

And we can take the square root of 4… which equals plus or minus 2...

01:13

so looks like the equation is true for all numbers equal to or between negative 2 and 2.

01:20

And the answer’s C.

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