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CAHSEE Math 3.1 Algebra and Functions 222 Views


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Description:

Algebra and Functions: Drill Set 3, Problem 1. Evaluate the expression.

Language:
English Language

Transcript

00:03

And here's your shmoop du jour.

00:06

Evaluate the expression 3x3 - 4y-2 for  x = 3 and y = 2.

00:15

Here are the potential answers...

00:16

Before we spoil the ending, hit pause and try it yourself.

00:23

Can we plug in numbers? Yes we can.

00:27

If we substitute 3 as x and 2 as y, we can

00:30

rewrite the equation as 3 times 3 cubed minus 4 times 2 to the negative second...

00:36

3 cubed is 27... and 3 times 27 is 81 and we're done with the first part

00:43

Now for the y's.

00:44

Don't forget that little negative sign next to the 2 in the exponent.

00:49

Remember that negative exponents basically just mean "1 over"...

00:53

...so we can move the y squared into the denominator...

00:55

...and rewrite that second part as 4 over 2 squared. 2 squared is 4. 4 over 4 is 1.

01:02

We subtract one from 81 and we get 80. Answer: D

01:06

Plugging has never been more fun.

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