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Solve for x: the quantity of x plus 4 all over 2 = 7.

x = 3

x = 5

x = 6

x = 10

Guest Jul 21, 2014

Best Answer 

 #4
avatar+91051 
+5

I just gave you 3 points Mari,      I don't give points as easily as CPhill does.  I like people to really earn them.

I am really pleased that you explained how you got your answer.  It was your explanation - not your answer that earned you your points with me.

 

You sort of did what CPhill did - I will try to explain.

$$\dfrac{(x+4)}{2}=7$$  

You sort of said :  What divided by 2=7 and the answer is 14/2 is 7   This means that x+4=14

CPhill said : I want to get the x+4 on its own so how do I get rid of the 2  Umm I muliply by 2 but if I multiply the left side by 2 then i have to multiply the right side by2 as well.  This keeps the equation balanced!

$$\begin{array}{rlll}
\frac{x+4}{2}&=&7\\\\
\frac{x+4}{2}\times 2&=&7\times 2\\\\
x+4&=&14\qquad \qquad \mbox{On the left the 2s cancel out, that is what CPhill did it for!}\\
\end{array}$$

Next you said :      What + 4=14 and the answer is obviously 10  SO    x=10

CPhill said:  x+4=14  I need the x by itself so how do I get rid of the +4 Umm  I know, I'll take it away (+4-4=0)

But if I take it away from the left side then I have to take it away from the right side too.  I have to keep the equation balanced!

x+4-4=14-4

x=10

See you sort of did the same thing only CPhill did it in a more formal way.

You need to learn how to do it the formal way or you will not be able to solve difficult equations later on.

 

ALWAYS REMEMBER - EQUATIONS ARE LIKE SCALES, THEY MUST STAY BALANCED AT ALL TIMES!

Melody  Jul 21, 2014
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10+0 Answers

 #1
avatar
0

the problem is (x+4)/2=7

Guest Jul 21, 2014
 #2
avatar+468 
+5

i dont really get how to do it. i just subsitute the numbers to see which one makes sense and i got 10

(10+4)/2=7

add 10+4 then divide it by 2 and it =7

14/2=7

mari379  Jul 21, 2014
 #3
avatar+78755 
+5

mari379, your "technique" will work if we're given the answers, beforehand.....!!!!

But, what if we don't have those???

Let's see how to solve this....step by step...

(x+4)/2=7       multiply both sides by 2

x + 4  = 14      subtract 4 from both sides

x = 10

In upper level maths....you have to be able to solve "without the answers"........also, "plugging" in the answers takes too much time in a test situation !!!!

 

CPhill  Jul 21, 2014
 #4
avatar+91051 
+5
Best Answer

I just gave you 3 points Mari,      I don't give points as easily as CPhill does.  I like people to really earn them.

I am really pleased that you explained how you got your answer.  It was your explanation - not your answer that earned you your points with me.

 

You sort of did what CPhill did - I will try to explain.

$$\dfrac{(x+4)}{2}=7$$  

You sort of said :  What divided by 2=7 and the answer is 14/2 is 7   This means that x+4=14

CPhill said : I want to get the x+4 on its own so how do I get rid of the 2  Umm I muliply by 2 but if I multiply the left side by 2 then i have to multiply the right side by2 as well.  This keeps the equation balanced!

$$\begin{array}{rlll}
\frac{x+4}{2}&=&7\\\\
\frac{x+4}{2}\times 2&=&7\times 2\\\\
x+4&=&14\qquad \qquad \mbox{On the left the 2s cancel out, that is what CPhill did it for!}\\
\end{array}$$

Next you said :      What + 4=14 and the answer is obviously 10  SO    x=10

CPhill said:  x+4=14  I need the x by itself so how do I get rid of the +4 Umm  I know, I'll take it away (+4-4=0)

But if I take it away from the left side then I have to take it away from the right side too.  I have to keep the equation balanced!

x+4-4=14-4

x=10

See you sort of did the same thing only CPhill did it in a more formal way.

You need to learn how to do it the formal way or you will not be able to solve difficult equations later on.

 

ALWAYS REMEMBER - EQUATIONS ARE LIKE SCALES, THEY MUST STAY BALANCED AT ALL TIMES!

Melody  Jul 21, 2014
 #5
avatar+468 
0

thank you melody! awesome and thanks for explaining it to me :)

mari379  Jul 21, 2014
 #6
avatar+78755 
0

Yeah....be careful, mari379........Melody is a "meanie".......(LOL!!!)

 

 

CPhill  Jul 21, 2014
 #7
avatar+91051 
0

YES 

When I was Queen Guinevere I would behead my unruly subjects!

And, now that I am a dinosaur I eat them for breakfast!

So you better tread VERY carefully.  lol.

Melody  Jul 21, 2014
 #8
avatar+78755 
0

Don't believe her for a minute, mari379.......her "bark" is worse than her "bite".....she's a "softy"....at heart.......

 

 

CPhill  Jul 21, 2014
 #9
avatar+11753 
0

Yes CPhill your right!these kinda people are really very soft of heart!

I wonder , Zegroes is Godzilla and Godzilla is much more than dinosaur so it means that Godzilla is much more soft of heart than dinosaur!

A new secret of POOR Zeg-ROSE has been revealed!

rosala  Jul 21, 2014
 #10
avatar+91051 
0

Sorry Chris

I didn't realise that it was a multiple choice answer. But it doesn't matter, my logic still holds. 

And what do you mean

"My bark is worse than my bite" ?

Got you bluffed.  Lol.

Anyway Mari it had been good to see you on the forum with the rest of CPhill's "Rat Pack".

Melody  Jul 21, 2014

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