8x-7=15+19x

amelia

New member
Joined
May 14, 2011
Messages
6
I know this appears to be a no brainer, but I am stuck on this.
I get
8x-7+7=15+7+19x
8x=22+19x
-19x+8x=22
-19x+19x+8x=22
8x=22?
yeah I can see this is not right, but where am I going wrong. obviously 8x2 does not equal 22
anyone? please forgive and look past my ineptness... :)
 

stapel

Super Moderator
Staff member
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Feb 4, 2004
Messages
15,943
amelia said:
8x-7+7=15+7+19x
8x=22+19x
-19x+8x=22
It appears that you left out the step between the second and third lines, being:

. . . . .8x - 19x = 22 + 19x - 19x

amelia said:
-19x+19x+8x=22
I do not understand how you got from your third line in the previous quote to this line...? :wink:
 
J

JeffM

Guest
amelia said:
-19x+8x=22
-19x+19x+8x=22

where am I going wrong
Stapel has given you all the help you should need for THIS problem, but remember the fundamental rule for manipulating equations:
Whatever you do to one side of the equation, you must do to the other.

Whenever you forget to use that rule, you will be in trouble.

On the plus side, you checked your work and so you knew that you had made an error. That is a REALLy important habit to acquire. Outside of school, avoiding mistakes is sometimes more important than finding the right answer.
 

Denis

Senior Member
Joined
Feb 17, 2004
Messages
1,473
amelia said:
8x-7+7=15+7+19x
8x=22+19x
-19x+8x=22
-19x+19x+8x=22
8x=22?
Amelia, please indicate clearly each step; a bit like:

8x - 7 = 19x + 15
Add 7 to both sides:
8x = 19x + 22
Subtract 19x from both sides:
-11x = 22
Divide both sides by -11:
x = -2

If you do that, then it's difficult to be wrong :wink:
 
F

funkybabeone

Guest
I think this is a new way to solve this problem...

8x - 7 = 15 + 19x
8x - 19x = 15 + 7
-11x = 22
x = -22/11
x = -2
 

Denis

Senior Member
Joined
Feb 17, 2004
Messages
1,473
funkybabeone said:
I think this is a new way to solve this problem...
8x - 7 = 15 + 19x
8x - 19x = 15 + 7
-11x = 22
x = -22/11
x = -2
This is not a new way, but the way mostly everybody uses once experienced with these.
I call it "switch to other side and change sign".
 

masters

Full Member
Joined
Mar 30, 2007
Messages
378
Denis said:
funkybabeone said:
I think this is a new way to solve this problem...
8x - 7 = 15 + 19x
8x - 19x = 15 + 7
-11x = 22
x = -22/11
x = -2
This is not a new way, but the way mostly everybody uses once experienced with these.
I call it "switch to other side and change sign".


And here is the general rule:

When known quantities are connected with the unknown quantity by the sign + or -, the equation is reduced by transposing the known quantities to the other side, and prefixing the contrary sign.

My [attachment=0:1yzq6p2v]2cents.jpg[/attachment:1yzq6p2v]

 

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J

JeffM

Guest
I have a suspicion that funkybabeone is a potential spammer.

There is another odd question under financial math posted at almost the same time under a different name.

Neither post really asks a question, and it is most surprising that the first posts made by two different people at almost the same time are not questions, but additions to an existing thread that has been inactive for a while.

I apologize if I am mistaken: my business experience tended to develop cyncism, which is an ugly attribute.
 
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