12-7(x-4)+x = -2
2007-05-12 11:57:40 · 9 answers · asked by Ari 2 in Science & Mathematics ➔ Mathematics
How do I prove that x=7?
2007-05-12 12:01:40 · update #1
Use the distributive property:
12 - 7(x - 4) + x = -2
12 - 7x + 28 + x = -2
-6x + 40 = -2
-6x = -42
x = 7
2007-05-12 12:00:19 · answer #1 · answered by eirikir 2 · 2⤊ 2⤋
Solve the "x" variable in the equation.
First: eliminate parenthesis - use the Distribution Method.
12 - 7(x) - 7(- 4) + x = -2
12 - 7x + 28 + x = -2
40 - 6x = -2
Sec: combine "like" terms - subtract 40 from both sides (when you move a term to the opposite side, always use the opposite sign).
40 - 40 - 6x = -2 - 40
- 6x = - 2 - 40
- 6x = - 42
Third: isolate the "x" variable on the left side - divide both sides by (-6).
- 6x/-6 = - 42/-6
x = 42/6
x = 7
2007-05-12 17:15:29 · answer #2 · answered by ♪♥Annie♥♪ 6 · 0⤊ 1⤋
multiply out the 7(x-4) first of all, then deal with the additions later on!
7(x-4)
-7x + 28 + x + 12 = -2
-6x +40 = -2
6x = 42
x=7
2007-05-12 12:01:49 · answer #3 · answered by Anonymous · 1⤊ 1⤋
12-7(x-4)+x = -2
12-7x+28 +x = -2
-6x + 40 = -2
-6x = -42
x = 7
2007-05-12 12:03:45 · answer #4 · answered by loslonelyboy 2 · 1⤊ 2⤋
You asked it already, and i gave you the answer. But i'll rewrite it here too:
12 - 7(x-4) + x = -2
Use distribution.
12- 7x +28 +x = -2
add alike terms.
40 - 6x = -2
What you do to one side, you have to do to the other, so add 6x to both sides to get the 6x on one side. This way, it can be positive. You don't have to but it's easier to understand this way. well... for me, anyways.
40 = 6x -2
add 2 to both sides to get all the numbers on one side and all the x's on the other.
42 = 6x
divide both sides by 7
7= x
2007-05-12 12:01:05 · answer #5 · answered by Anonymous · 1⤊ 2⤋
x = 7
First, distribute -7 into (x-4). You get:
12-7x+28+x = -2
Then, subtract 12 and 28 from one side of the = and get:
-7x+x = -42
Next, add -7x + 1x to get:
-6x = -42
Multiply -6 from each side and get:
x=7
2007-05-12 12:02:05 · answer #6 · answered by sam79241 3 · 1⤊ 2⤋
12-7(x-4)+x=-2
12-7x+28+x=-2
12-6x+28=-2
-12 -12
-6x+28=-14
-28 -28
-6x=-42
-6x/-1=6x
-42/-1=42
42/6=7 x=7
good luck!
2007-05-12 12:07:45 · answer #7 · answered by Anonymous · 0⤊ 2⤋
12-7x+28+x=-2
40-6x=-2
40-40-6x=-2-40
-6x=-42
-6x/-6=-42/-6
x=7
2007-05-12 12:04:57 · answer #8 · answered by Dave aka Spider Monkey 7 · 1⤊ 2⤋
lol i got -2.33333
but im so bad at math
sorry its probably wrong
2007-05-12 12:03:00 · answer #9 · answered by kcg4 2 · 1⤊ 2⤋