Line segment

[rachelmaddie]

I want to check my work.
Solve for x

CD = 9, DE = 3x + 6, CE = 36

9 + 3x + 6 = 36

3x + 15 = 36

Place the variable x on the left side and the numeric values on the right side.

3x = 36 - 15

3x = 21

x = 7

Substitute the value of x to prove the equation is true.

9 + 3(7) + 6 = 36

3(7) + 15 = 36

36 = 36

 

[tkhunny]

That's very clean and organized.

I might have wanted just one more thing:

Before writing [math]9 + 3x + 6 = 36[/math], the algebra version of the problem, it might be good to write the geometry version of the problem, since it was presented as a geometry problem, maybe [math]\overline{CD} + \overline{DE} = \overline{CE}[/math].

 

[rachelmaddie]

That's very clean and organized.

I might have wanted just one more thing:

Before writing [math]9 + 3x + 6 = 36[/math], the algebra version of the problem, it might be good to write the geometry version of the problem, since it was presented as a geometry problem, maybe [math]\overline{CD} + \overline{DE} = \overline{CE}[/math].

I did put that but I deleted it because I wasn’t sure if it was correct.

 

[tkhunny]

I did put that but I deleted it because I wasn’t sure if it was correct.

You know what that is? Being awesome!

 

[rachelmaddie]

You know what that is? Being awesome!

How do I provide a geometric explanation for that?

 

[tkhunny]

It is sufficient as I have written it. Just show that the line segments add up.

 

[tkhunny]

Since you're so close to perfect on this, I might add that your equation might be just a little easier to follow if you first write it like this:

[math]9 + (3x + 6) = 36[/math]
This emphasizes just how precisely the algebra statement matches the geometry statement.

 

[rachelmaddie]

It is sufficient as I have written it. Just show that the line segments add up.

Substitute the value of x
3(7) + 6
3(7) + 6 = 27
27 + 9 = 36

 

[tkhunny]

Well, after you write the algebra equation, we don't necessarily need to make any more geometry statements. The geometry led to the algebra. The algebra led to the final result, [math]x = 7[/math]. Checking your answer is not part of the solution. It should be part of your process.

 

[rachelmaddie]

Well, after you write the algebra equation, we don't necessarily need to make any more geometry statements. The geometry led to the algebra. The algebra led to the final result, [math]x = 7[/math]. Checking your answer is not part of the solution. It should be part of your process.

So where in the process would I include that?

 

[tkhunny]

There is nothing lacking in your presentation. What do you think you are missing?

 

[rachelmaddie]

There is nothing lacking in your presentation. What do you think you are missing?

only because you said to show that the line segments add up.

 

[tkhunny]

Right. That was in my first response. No more than that.