Easy Proofs

Easy Proofs

Ms. Anderson

What is a Proof?

A proof is the process you go through to prove something is true...we all like to be right don't we?!

Example

 $GIVEN:\ 4\left(2x-7\right)=8\ PROVE:\ x=7.5$  
Our first step is to start with what we are given, what we know

Multiple Choice

What is our first step in our proof?

• x= 7

• 6x-28=8

• 4(2x-7)= 8

• 6x=36

Next Step

Our next step will be trying to get our prrog closer to what we are trying to prove.

so... $4\left(2x-7\right)=8$  

to get rid of that 4, we have to distribute or multiply it, by the 2x and -7 

Poll

What do you think the next step will look like now? Go back and look if you need to.

• 8x=60

• 8x-28=8

• x=7.5

Almost There!

Now that our equation has been distributed, it should look like this...

 $8x-28=8$  

Multiple Choice

What do we need to do next?

• Add the 28 to both sides

• Subtrate the 28 from both sides

• Subtrate the 8

Finished.... Almost

We have just one last teeny weeny step before our proof is done...

 $8x=60$  

Multiple Choice

What is our answer after we divide?

• 5.5

• 7

• 7.5

• 3