the problem is 4x - 9 = 7x + 12
thanx so much!!! please dont tell me i need to do my own homework!!!
2006-09-07 11:01:03 · 24 answers · asked by Ashley 2 in Education & Reference ➔ Homework Help
hmmm well good news i learned this k hold on......................105
2006-09-07 11:03:20 · answer #1 · answered by Anonymous · 1⤊ 0⤋
you simply move all the numbers with variables on one side of the equal sign and keep the normal numbers on the other.
IMPORTANT: Whenever you move numbers to the other side, you must change the sign to make it the opposite. For ex. if you move 7x to where the 4x is, it will turn to -4x, negative. And the same thing for -9, it will turn to +9 when you move it over with the 12. So you're problem will look something like:
4x-7x = 12+9
Then you subtract 4x-7x which is -3x
And 12+9 = 21
Now you have: -3x= 21
This is where people have trouble.
Your goal is to have the x by itself so it can say x = w/e
Since -3x is being multiplied together you do the opposite (divide) when you bring it over with the 21.
So now x= 21 / -3
x= ____ (don't forget the negatives!)
You tell me! hehe
Hope ya get it ;-)
2006-09-07 18:09:12 · answer #2 · answered by Alybaba 2 · 1⤊ 0⤋
So I take it you don't want the answer?
So I assume you just want a simple description as to how to perform the calculations.
When you look at an equation, the left side has to equal the right side, right? Because it has an equal sign of course.
You can manipulate both sides to make it more managble and solvable. But the secret to this is that whatever you do to one side, you must do it to the other side so that each side is still 'equal'.
So the equation:
4x - 9 = 7x + 12
Let's try and put all the x terms on the right side, and the constants on the left side.
So first subtract 4x from each side to get ride of the x term on the left side. We then end up with something that looks like:
-9 = 3x + 12
This is because 4x - 4x = 0 and 7x - 4x = 3x
Next lets subtract 12 from both sides so that we take the constant away from the right side.
We get:
-21 = 3x
We can also multiply and divide each side as well.
And we can see that to make x by itself we must divide by 3:
3x/3 = x (ie 3/3 = 1)
so:
-21/3 = 3x/3
so -7 = x
or x = -7
try this method on another example for yourself to see.
2006-09-07 18:02:28 · answer #3 · answered by o0twiggles0o 3 · 1⤊ 1⤋
4x - 9 = 7x + 12
-12 -4x -12 -4x
-21=3x
/3 /3
-7 =x Answer
2006-09-07 18:06:49 · answer #4 · answered by Kelsey 3 · 1⤊ 0⤋
-9-12 = 7x-4x
-21=3x
-7=x
2006-09-07 18:28:57 · answer #5 · answered by Anonymous · 1⤊ 0⤋
4x - 9 = 7x + 12
-9 - 12 = 7x - 4x
-21 = 3x
x = -21/3
x = -7
2006-09-07 18:04:59 · answer #6 · answered by prawn_headed 5 · 1⤊ 0⤋
Rearrange the equation to get all the x's on the same side, by adding and subtracting the same thing from both sides.
4x - 7x = 12 + 9
- 3x = 21
divide both sides by -3
x = -7
Aloha
2006-09-07 18:04:40 · answer #7 · answered by Anonymous · 1⤊ 0⤋
like terms on same side... Whatever you do to 1 side, do to the other:
4x - 9 = 7x + 12
-4x .........-4x
-9 = 3x + 12
-12 .........-12
-21 = 3x
(1/3)-21 = 3x(1/3)
-7 = x
substitute back into original equation to check...
2006-09-07 18:07:10 · answer #8 · answered by KnowhereMan 6 · 1⤊ 0⤋
Move all the x factors to one side (subtract 4x from each side. Hint: the right side will be 7x - 4x). Move all the non-x factors to the other side (subtract 12 from each side). Divide the non-x side by the factor in front of the x. For instance, if it is 3x, divide each side by 3. That will give you x = a number (your answer).
2006-09-07 18:05:39 · answer #9 · answered by just browsin 6 · 1⤊ 0⤋
First add the 9 to each side.
Now you have 4x = 7x+21
Next, subtract the 7x from each side.
Now you have -3x = 21
Next, divide each side by -3.
Now you have x = -7
2006-09-07 18:03:54 · answer #10 · answered by magchug13 2 · 1⤊ 0⤋
Okay so get all the x's on one side of the equation.....
7x-4x = -9-12
therefore...
3x = -21
therefore
x = -21/3 = -7
geddit sister?
2006-09-07 18:08:36 · answer #11 · answered by Anonymous · 1⤊ 0⤋