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Basic Operations Videos 58 videos

Operations with Rational Expressions
8687 Views

It's impressive that these expressions are able to stay so rational even when they're having operations performed on them.

Numbers and Operations: Elementary Number Theory
606 Views

Jack and Jill went up the hill to fetch a pail of water. But what happened when they got up there? They’ve been gone an awfully long time…

SAT Math 7.3 Algebra and Functions
318 Views

SAT Math 7.3 Algebra and Functions

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Two-Step Equations Using Multiplication/Division 4115 Views


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Description:

This video helps you tackle two-step equations with multiplication and division by using the opposite operation on each side of the equation. Definitely less scary than laser sharks!

Language:
English Language
Common Core Standards:

Transcript

00:04

Two-Step Equations Using Multiplication and Division , a la Shmoop.

00:12

After returning from vacation, Dr. Villain comes home to find he has only one laser-shark

00:17

left.

00:18

His man-servant, Bill, explains that the first half were killed by flesh-eating bacteria.

00:24

And then he ate another three because he'd forgotten to go grocery shopping.

00:34

Can you determine how many sharks Dr. Villain had before his Jamaican getaway?

00:41

As always, we'd like to have a formula to help us solve the problem.

00:45

So we first need to determine the variable.

00:49

Because we're trying to figure out the original number of sharks, we're going to substitute

00:53

that value with x. In the beginning, there were x number of sharks.

00:59

Then half were eaten by flesh-eating bacteria. We'll write that as x over 2.

01:03

Guess someone should have washed their hands a little better.

01:11

Then Bill ate three of the sharks, so we'll subtract 3.

01:15

We know there was only one shark left, so we can put 1 to the right of the equals sign.

01:21

Our goal is to get x all by itself on one side. So let's first get rid of that pesky

01:26

-3.

01:27

We can do that by using the opposite operation and adding 3 to both sides.

01:34

Remember to always perform the same operation on both sides; Dr. Villain is fair that way.

01:40

Now we have x divided by 2 equals 4.

01:44

While we can't undo the near-extinction of the laser-shark, we can undo x being divided

01:49

by 2... by multiplying 2 to both sides. And there you have it, Villains and Man-Servants:

01:57

x equals 8.

02:01

Which means the original number of laser-sharks totaled 8.

02:06

Hey there, turn that frown upside down, Dr. Villain.

02:11

You may only have one laser-shark left. But even a sad, friendless laser-shark is still

02:16

a laser shark!

02:20

Just remember that, in the future, you might want to hire better help...preferably someone

02:24

who doesn't have a taste for laser shark.

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