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Basic Algebra Videos 43 videos

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CAHSEE Math 4.2 Number Sense 205 Views


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Description:

Number Sense: Drill Set 4, Problem 2. Simplify the expression.

Language:
English Language

Transcript

00:03

And here's your shmoop du jour.

00:06

Simplify the expression (4a to the -2) quantity to the -1.

00:12

And here are the possible answers...

00:18

Ok, this question is testing whether we have learned to love the negative exponent.

00:22

And yeah, negative exponents just mean "one over", more or less.

00:28

Remember order of operations, or PEMDAS?

00:31

This tells us that we have to start with the parentheses to simplify this expression.

00:37

So let's start in the middle of the cave and clean up the mess in... 4a to the -2.

00:43

Think about this one as 4 times... big pause...

00:46

"a" to the -2.

00:49

That is, first get "a" to the -2 to be 1 over "a" squared.

00:54

That'll help simplify things a lot. And we then have 4 times that number...

00:58

which gives us 4 over "a" squared. Now that we've manipulated the inside of the

01:03

parentheses, we can work on the exponent.

01:05

So think of 4 over "a" squared as one unit for now, one thing that can't be changed...

01:10

for a moment anyway.

01:12

That whole chunk of number is now placed to the -1...

01:15

...which means that we take one OVER that number to then get rid of the negative exponent

01:19

thingy... which is just too odd to digest. So we have 1 OVER the quantity 4 over "a" squared.

01:26

Remember that dividing by a fraction is the same as multiplying the inverse -- so let's do that.

01:34

We get one TIMES "a" squared over 4. Which is just "a" squared over 4.

01:40

And ta-da.. the answer is B.

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