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Vanity: Are you smarter than a 7th grader? (Need help with my kid's algebra homework)

Posted on 01/18/2012 6:08:38 PM PST by Maceman

The problem is:

3-4x = 6X+13

Can someone (please) demonstrate how to solve this? (I always was terrible at math).

Thanks.


TOPICS: Your Opinion/Questions
KEYWORDS: algebra; homework; math; vanity
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1 posted on 01/18/2012 6:08:42 PM PST by Maceman
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To: Maceman
X=-1

Add 4x to both sides:

3=10x+13

Subtract 13 from both sides

-10=10x

Divide by 10: -1=x

2 posted on 01/18/2012 6:10:24 PM PST by ShadowAce (Linux -- The Ultimate Windows Service Pack)
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To: Maceman

Negative ONE is the loneliest...


3 posted on 01/18/2012 6:10:59 PM PST by TFine80
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To: Maceman

Easy peasy...balance the equation.

Get all the x’s on onside, all the whole’s on the other and then divide to find x.

sorry no answer from me...do the homework.


4 posted on 01/18/2012 6:11:13 PM PST by EBH (God Humbles Nations, Leaders, and Peoples before He uses them for His Purpose)
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To: Maceman

3 - 4x = 6X + 13

3-4x (+4x) = 6X+13 (+4x)

3 = 10x + 13

3 (-13) = 10x + 13 (-13)

-10 = 10x

-10/10 = x

-1=x


5 posted on 01/18/2012 6:13:14 PM PST by Pan_Yan
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To: Maceman

3-4x = 6X+13
+4x = +4x
____________
3 = 10x +13
-13 = -13
____________
-10 = 10x
Divide by 10
____________
1- = x


6 posted on 01/18/2012 6:13:59 PM PST by Jeff Chandler (Quando Omni Flunkus Moritati)
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To: Maceman

3-4x = 6X+13
+4x = +4x
____________
3 = 10x +13
-13 = -13
____________
-10 = 10x
Divide by 10
____________
-1 = x


7 posted on 01/18/2012 6:14:26 PM PST by Jeff Chandler (Quando Omni Flunkus Moritati)
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To: Maceman

WTF?? Get off FR and go to wolframalpha.com.


8 posted on 01/18/2012 6:14:42 PM PST by indianrightwinger
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To: ShadowAce

After solving ( X = -1), then put it into the original equation to check your work.

3 - 4x = 6x + 13
3 - 4*-1 = 6*-1 + 13
3 +4 = -6 + 13
7 = 7


9 posted on 01/18/2012 6:16:51 PM PST by mason-dixon (As Mason said to Dixon, you have to draw the line somewhere.)
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To: Maceman
Check out Khan Academy. He has all the answers...and your kid will be an A student ASAP!
10 posted on 01/18/2012 6:17:02 PM PST by RoosterRedux (Newt: "Why vote for the guy who lost to the guy who lost to Obama?")
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To: Maceman

Algebra solver- solves and explains your problem

http://quickmath.com/webMathematica3/quickmath/page.jsp?s1=equations&s2=solve&s3=basic


11 posted on 01/18/2012 6:17:18 PM PST by patriot08 (TEXAS GAL- born and bred and proud of it!)
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To: Maceman

X= -1

Did it in my head in about 3 seconds.


12 posted on 01/18/2012 6:17:49 PM PST by SeaHawkFan
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To: SeaHawkFan

bfl


13 posted on 01/18/2012 6:20:21 PM PST by Oshkalaboomboom
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To: indianrightwinger

good advice about a great web site


14 posted on 01/18/2012 6:20:38 PM PST by Nifster
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To: Maceman

http://www.webmath.com

This is a website that we always use. It solves the problem, but also shows how to get the answer.


15 posted on 01/18/2012 6:24:01 PM PST by silly.kerry.trix.are.for.kids
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To: Maceman

16 posted on 01/18/2012 6:28:27 PM PST by Drango (A liberal's compassion is limited only by the size of someone else's wallet.)
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To: Maceman

http://www.purplemath.com/modules/index.htm


17 posted on 01/18/2012 6:34:40 PM PST by US Navy Vet (Go Packers! Go Rockies! Go Boston Bruins! See, I'm "Diverse"!)
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18 posted on 01/18/2012 6:36:25 PM PST by TheOldLady (FReepmail me to get ON or OFF the ZOT LIGHTNING ping list)
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To: Drango

You are correct.


19 posted on 01/18/2012 6:38:24 PM PST by AceMineral (Some people are too stupid for their own good.)
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To: Maceman
#!/usr/bin/perl

$x= -101;
while ($x < 101){
	$a= 3-(4*$x);
	$b= (6*$x)+13;
	if ($a == $b){ print "$x\n";}
	$x++;
}

I'm a big believer in brute force. ;)

/johnny

20 posted on 01/18/2012 6:39:15 PM PST by JRandomFreeper (Gone Galt)
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To: Maceman

3-4x = 6X+13

-4x - 6x = 13 - 3

-10x = 10

x = -1


21 posted on 01/18/2012 6:39:19 PM PST by 353FMG
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To: Maceman
3-4x = 6X+13

3-4x-6x = 13

-10x = 13-3

-10x = 10

-x = 1

x = -1

22 posted on 01/18/2012 6:48:32 PM PST by Yashcheritsiy
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To: Maceman

This is the second simple Algebra problem to appear on FR in a week:

http://www.freerepublic.com/focus/f-chat/2830903/posts

“Verrry interestink.” —Artie Johnson


23 posted on 01/18/2012 6:49:13 PM PST by BradyLS (DO NOT FEED THE BEARS!)
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To: Maceman
Also, x1/2 = i or -i
24 posted on 01/18/2012 6:51:58 PM PST by Yashcheritsiy
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To: Maceman
If I could spell "Algebra" I will tell you in my miniscule brain x never equals a number, I mean WTH! how can a letter equal a number.

Algebra is obviously a tool of the devil! it is evil!

Trust me, I used to be from the government, and I am here to help.

25 posted on 01/18/2012 6:53:28 PM PST by SERE_DOC (My Rice Krispies told me to stay home & clean my weapons!)
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To: Maceman

All you need is a good calculator.

(...my imitation of the NEA)


26 posted on 01/18/2012 6:53:46 PM PST by BobL ("Heartless" and "Inhumane" FReepers for Cain - we've HAD ENOUGH)
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To: Drango

I’m just glad it wasn’t 7x13!

http://www.youtube.com/watch?v=0K-yV91PBbE

(Abbott and Costello!)


27 posted on 01/18/2012 6:54:25 PM PST by 21twelve
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To: SeaHawkFan
I still remember that feeling of ecstacy the first time I solved an equation with 6 unknowns.

Yeh...I did it my head, too. Agebra is a simple game of rules.

28 posted on 01/18/2012 6:57:41 PM PST by Sacajaweau
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To: SeaHawkFan
I still remember that feeling of ecstacy the first time I solved an equation with 6 unknowns.

Yeh...I did it my head, too. Algebra is a simple game of rules.

29 posted on 01/18/2012 6:57:50 PM PST by Sacajaweau
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To: Maceman

Use ‘the scientific method’ :

Toss the teacher into water.
If she doesn’t drown she’s possessed and you’ll have to burn her of course.
If she drowns- well- at least you won’t have to spend valuable drinking time doing kid’s homework anymore.


30 posted on 01/18/2012 7:01:47 PM PST by mrsmith (What Tea Party nominee have you found for your House seat?)
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To: Maceman

Obviously others have provided the answer, but what you need to understand is how to solve an equation. It’s an equation because both sides are equal, right?

So what you do to one side of the equation, you must do to the other side of the equation to keep it “equal.”

So to simplify the equation, move the whole numbers to one side and the unknowns (x’s) to the other.

You can move the 3 or the 13 first. It doesn’t matter which one, just pick one. To remove the 13 from the right side, subtract it. Since both sides must remain equal, you must subtract 13 from the left side too.

That leaves:

3 - 4x - 13 = 6x + 13 - 13

which is:

-10 - 4x = 6x

Now move the 4x from the left side to the right side. To do so, add 4x to both sides:

-10 - 4x + 4x = 6x + 4x

which is:

-10 = 10x

So 10 times what equals -10?

x = -1

(Last step is dividing both sides by 10 to move the 10 from the right side to the left side.)


31 posted on 01/18/2012 7:06:35 PM PST by BuckeyeTexan (Man is not free unless government is limited. ~Ronald Reagan)
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To: Maceman; mrreaganaut

I see you got the help you needed. One of the things I love about Freep is that people post threads like this.


32 posted on 01/18/2012 7:08:52 PM PST by reaganaut (If Romney is a conservative then I'm the frickin Angel Moroni.)
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To: Drango
So classic: x = 5cm
33 posted on 01/18/2012 7:16:14 PM PST by reg45 (I'm not angry that Lincoln freed the slaves. I'm angry that Franklin Roosevelt bought them back.)
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To: Maceman

Because Algebra is an arabic word, I refuse to do it on religious grounds. But I think the derivative of x is zero.


34 posted on 01/18/2012 7:17:20 PM PST by ALPAPilot
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To: JRandomFreeper

Haha, awesome. ;)


35 posted on 01/18/2012 7:18:39 PM PST by lefty-lie-spy (Stay metal. For the Horde \m/("_")\m/ - via iPhone from Tokyo.)
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To: Maceman
Algebra: invented by ancient geeks who couldn't figure out what the "Y" was.

"Yeah, well, your girlfriend might look hot in her toga, but I know what "X" is!"

Pfffffft!

36 posted on 01/18/2012 7:19:27 PM PST by DTogo (High time to bring back the Sons of Liberty !!)
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To: lefty-lie-spy
Since I'm just a cook, it only works on integers. ;)

/johnny

37 posted on 01/18/2012 7:23:46 PM PST by JRandomFreeper (Gone Galt)
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To: Pan_Yan

But suppose x were -5.

3 - (4 * -5) would be -17.

(6 * -5) + 13 would also be -17.

So why is your answer right and mine....er, whatever.


38 posted on 01/18/2012 7:29:12 PM PST by proxy_user
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To: Maceman

3-4x = 6X+13
3 - 4x + 4x = 6x + 4x + 13
3 = 10x + 13
3 - 13 = 10x + 13 - 13
-10 = 10x
-1 = x


39 posted on 01/18/2012 7:35:00 PM PST by RaceBannon (Ron Paul is to the Constitution what Fred Phelps is to the Bible.)
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To: Maceman

Math is easy. Just watch these experts and you’ll learn a lot ...

http://www.youtube.com/watch?v=rLprXHbn19I


40 posted on 01/18/2012 7:36:13 PM PST by CapnJack
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To: proxy_user

Ach, I see what I did wrong. Had myself worried there for a minute. I’m going to bed.


41 posted on 01/18/2012 7:38:52 PM PST by proxy_user
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To: Maceman
3-4x = 6X+13

Didn't we just have this a few days ago?

3-4x = 6x+13
-4x-6x =13-3
-10x = 10
x = 10/-10
x = -1
42 posted on 01/18/2012 7:40:20 PM PST by aruanan
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To: JRandomFreeper

hey, wait, you didnt declare a or b as variables that wont work!

:)


43 posted on 01/18/2012 7:43:05 PM PST by RaceBannon (Ron Paul is to the Constitution what Fred Phelps is to the Bible.)
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To: Maceman

I couldn’t pass algebra, so I became an Electrical Engineer. : )


44 posted on 01/18/2012 7:44:27 PM PST by jmax
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To: ShadowAce

Either you are right, or else the answer is 42.


45 posted on 01/18/2012 7:45:41 PM PST by FlyingEagle
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To: JRandomFreeper

Ha-ha! Peace through superior firepower, huh?


46 posted on 01/18/2012 7:47:27 PM PST by Slump Tester (What if I'm pregnant Teddy? Errr-ahh -Calm down Mary Jo, we'll cross that bridge when we come to it)
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To: Drango

47 posted on 01/18/2012 7:50:38 PM PST by PrinterEagle
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To: Maceman

When my eldest was in 7th grade I decided to go to a nearby college and take a college math class so that I could remember everything I had long forgotten , I was never sorry I did that ...


48 posted on 01/18/2012 8:04:13 PM PST by RnMomof7
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To: Pan_Yan

You worked it as I would have..we must have had the same beginning algebra book :)


49 posted on 01/18/2012 8:06:58 PM PST by RnMomof7
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To: BuckeyeTexan
very concisely stated !
50 posted on 01/18/2012 8:08:23 PM PST by builder (I don't want a piece of someone else's pie)
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