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Which best explains why the equation 4x+5=4x-1 has no solutions? A. the equation has a variable on both sides. B. The equation is true for any value of x. C. The equation is not true for any value of x.

 Aug 4, 2014

Best Answer 

 #1
avatar+3454 
+8

Let's see here. We have three options.

A. The equation has a variable on both sides.

B. The equation is true for any value of x.

C. The equation is not true for any value of x.

 

A would not be true, because you can still solve for x even if there is x (a variable) on both sides.

Think about it, if you had something like 5x+3=2x-9, you could still solve for x. This equation has a variable on both sides.

 

B would not be true, and we could prove that by putting a couple values of x into the equation. Let's try 4 and 15.

\begin{array}{rll}  4x+5&=&4x-1\\  4(4)+5&=&4(4)-1\\  16+5&=&16-1\\  21&\neq&15  \end{array}  \boxed{21&\neq&15}\\    \begin{array}{rll}  4x+5&=&4x-1\\  4(15)+5&=&4(15)-1\\  60+5&=&60-1\\  65&\neq&59  \end{array}  \boxed{65\neq59}

 

Finally, we can just prove our answer is C by putting in values for x.

Nomatter which value you put in for x, there will never be a solution for x.

 Aug 4, 2014
 #1
avatar+3454 
+8
Best Answer

Let's see here. We have three options.

A. The equation has a variable on both sides.

B. The equation is true for any value of x.

C. The equation is not true for any value of x.

 

A would not be true, because you can still solve for x even if there is x (a variable) on both sides.

Think about it, if you had something like 5x+3=2x-9, you could still solve for x. This equation has a variable on both sides.

 

B would not be true, and we could prove that by putting a couple values of x into the equation. Let's try 4 and 15.

\begin{array}{rll}  4x+5&=&4x-1\\  4(4)+5&=&4(4)-1\\  16+5&=&16-1\\  21&\neq&15  \end{array}  \boxed{21&\neq&15}\\    \begin{array}{rll}  4x+5&=&4x-1\\  4(15)+5&=&4(15)-1\\  60+5&=&60-1\\  65&\neq&59  \end{array}  \boxed{65\neq59}

 

Finally, we can just prove our answer is C by putting in values for x.

Nomatter which value you put in for x, there will never be a solution for x.

NinjaDevo Aug 4, 2014
 #2
avatar+118703 
+3

hi Ninja,

You are starting to use LaTex in ways that I have not used it. 

I think I know how you put the boxed results on the right but I will need to play before I am sure.  Thanks.

I will be learning all sorts of things off you soon.  I am very impressed !!

 Aug 5, 2014
 #3
avatar+3454 
+5

Hey Melody,

I actually didn't mean for the boxed numbers to be on the side like they did, it actually came by accident. Lol!

Maybe you can explain why this happened. I basically just ended the array, then put in the box command and it appeared on the side like so. I was hoping to box the not equal sign that's already centered, but when I tried to box it, it just kept spooling and didn't give me a result in the output box.

The highlighted is what I was trying to box:

 

Here's my code:

\begin{array}{rll}

4x+5&=&4x-1\\

4(4)+5&=&4(4)-1\\

16+5&=&16-1\\

21&\neq&15

\end{array}

\boxed{21&\neq&15}\\

\begin{array}{rll}

4x+5&=&4x-1\\

4(15)+5&=&4(15)-1\\

60+5&=&60-1\\

65&\neq&59

\end{array}

\boxed{65\neq59}

 

Any help is appreciated. :)

 Aug 5, 2014
 #4
avatar+118703 
+5

It happened because you did not put \\ after \end{array}

I've done it accidentally before too but I've never experimented to see how it can be useful.

Soon I will be learning off you - I am already starting too!  

 Aug 5, 2014

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