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SAT Math Videos 171 videos

SAT Math 1.1 Algebra and Functions
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SAT Math 1.1 Algebra and Functions. Find an algebraic equation to correspond with the data.

SAT Math 1.1 Geometry and Measurement
719 Views

SAT Math 1.1 Geometry and Measurement. What is the circumference of the circle?

SAT Math 1.1 Numbers and Operations
280 Views

SAT Math 1.1 Numbers and Operations. How many combinations of beverage and cereal can be made?

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SAT Math 3.1 Algebra and Functions 250 Views


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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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