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

[Maceman]

The problem is:

3-4x = 6X+13

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

Thanks.

[ShadowAce]

X=-1

Add 4x to both sides:

3=10x+13

Subtract 13 from both sides

-10=10x

Divide by 10: -1=x

[TFine80]

Negative ONE is the loneliest...

[EBH]

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.

[Pan_Yan]

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

[Jeff Chandler]

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

[Jeff Chandler]

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

[indianrightwinger]

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

[mason-dixon]

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

[RoosterRedux]

Check out Khan Academy. He has all the answers...and your kid will be an A student ASAP!

[patriot08]

Algebra solver- solves and explains your problem

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

[SeaHawkFan]

X= -1

Did it in my head in about 3 seconds.

[Oshkalaboomboom]

bfl

[Nifster]

good advice about a great web site

[silly.kerry.trix.are.for.kids]

http://www.webmath.com

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

[Drango]

[US Navy Vet]

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

[TheOldLady]

Boop His Tiny Tail!

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Please Donate Monthly!

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For each new monthly sign-up

[AceMineral]

You are correct.

[JRandomFreeper]

#!/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

[353FMG]

3-4x = 6X+13

-4x - 6x = 13 - 3

-10x = 10

x = -1

[Yashcheritsiy]

3-4x = 6X+13

3-4x-6x = 13

-10x = 13-3

-10x = 10

-x = 1

x = -1

[BradyLS]

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

[Yashcheritsiy]

Also, x^1/2 = i or -i

[SERE_DOC]

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.

[BobL]

All you need is a good calculator.

(...my imitation of the NEA)

[21twelve]

I’m just glad it wasn’t 7x13!

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

(Abbott and Costello!)

[Sacajaweau]

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.

[Sacajaweau]

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.

[mrsmith]

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.

[BuckeyeTexan]

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.)

[reaganaut]

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

[reg45]

So classic: x = 5cm

[ALPAPilot]

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

[lefty-lie-spy]

Haha, awesome. ;)

[DTogo]

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!

[JRandomFreeper]

Since I'm just a cook, it only works on integers. ;)

/johnny

[proxy_user]

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.

[RaceBannon]

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

[CapnJack]

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

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

[proxy_user]

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

[aruanan]

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

[RaceBannon]

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

:)

[jmax]

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

[FlyingEagle]

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

[Slump Tester]

Ha-ha! Peace through superior firepower, huh?

[PrinterEagle]

[RnMomof7]

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 ...

[RnMomof7]

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

[builder]

very concisely stated !