4+-3(7+2x)/5+18.5=-74.9
I know the answer is 75 but when do it I keep getting -237.5
Tell me what I am doing wrong?!
Easy algebra??With work??Help?
2008-10-12 3:21 pm
回答 (11)
2008-10-12 3:40 pm
✔ 最佳答案
I don't know what you're doing wrong exactly, but maybe there is something wrong with the way you typed the problem. You wrote: 4+-3(7+2x)/5+18.5 = -74.9
Shouldn't it be [ 4+-3(7+2x) ] / 5+18.5 = -74.9 ?
You can add, subtract, divide, and multiply each side by the same thing. (Except divide by zero is not allowed.)
Subtract 18.5 from each side, and get:
[4+ -3 (7 + 2x)] / 5 = -93.4
Multiply each side by 5:
[ 4 + - 3 (7 + 2x) ] = -467
4 + - 3 (7 + 2x) = -467
Subtract 4 from each side
- 3 (7 + 2x) = -471
Divide each side by -3
(7 + 2x) = 157
7 + 2x = 157
Subtract 7 from each side
2x = 150
Divide each side by 2
x = 75
2008-10-12 10:53 pm
4 + (- 3[7 + 2x]/5) + 18.5 = - 74.9
(- 21 - 6x)/5 = - 97.4
- 21 - 6x = - 487
6x = 466
x = 233/3 or 77 2/3
Answer: 233/3 or 77 2/3
Proof:
4 + (- 3[7 + 2{233/3}]/5 + 18.5 = - 74.9
22.5 + (- 3[21/3 + 466/3]/5) = - 74.9
22.5 + (- 3[487/3]/5) = - 74.9
22.5 - 487/5 = - 74.9
22.5 - 97.4 = - 74.9
- 74.9 = - 74.9
(- 21 - 6x)/5 = - 97.4
- 21 - 6x = - 487
6x = 466
x = 233/3 or 77 2/3
Answer: 233/3 or 77 2/3
Proof:
4 + (- 3[7 + 2{233/3}]/5 + 18.5 = - 74.9
22.5 + (- 3[21/3 + 466/3]/5) = - 74.9
22.5 + (- 3[487/3]/5) = - 74.9
22.5 - 487/5 = - 74.9
22.5 - 97.4 = - 74.9
- 74.9 = - 74.9
2008-10-12 10:53 pm
4+-3(7+2x)/5+18.5 = -74.9
take 4 and 18.5(22.5 total) from both sides
-3(7+2x)/5 = - 97.4
multiply both sides by -5
3(7+2x) = 487.0
Divide both sides by 3
7 + 2x = 162.3333
take 7 from both sides
2x = 155.3333
divide both sides by 2
x = 77.6666
take 4 and 18.5(22.5 total) from both sides
-3(7+2x)/5 = - 97.4
multiply both sides by -5
3(7+2x) = 487.0
Divide both sides by 3
7 + 2x = 162.3333
take 7 from both sides
2x = 155.3333
divide both sides by 2
x = 77.6666
2008-10-12 10:45 pm
4 + (-3)(7 + 2x)/5 + 18.5 = -74.9
4 + (-21 - 6x)/5 = -74.9 - 18.5
(-21 - 6x)/5 = -93.4 - 4
-21 - 6x = 5(-97.4)
-6x = -487 + 21
x = -466/-6
x â 77.67
4 + (-21 - 6x)/5 = -74.9 - 18.5
(-21 - 6x)/5 = -93.4 - 4
-21 - 6x = 5(-97.4)
-6x = -487 + 21
x = -466/-6
x â 77.67
2008-10-12 10:37 pm
4 -(21+6x)/5 +18.5 = -74.9
-(21+6x)/5 = -74 -18.5-4 = -97.4
-(21+6x) = -487
-6x = - 466
x = 77 2/3
It appears that you left out some parentheses and the problem should be written as:
(4 -3(7+2x))/5 +18.5 = -74.9
-(21+6x)/5 = -74 -18.5-4 = -97.4
-(21+6x) = -487
-6x = - 466
x = 77 2/3
It appears that you left out some parentheses and the problem should be written as:
(4 -3(7+2x))/5 +18.5 = -74.9
2008-10-12 10:37 pm
4+-3(7+2x)/5+18.5=-74.9
4+-3(7+2x)/5=-93.4
-3(7+2x)/5 = -97.4
7+2x = 487/3
2x = 487/3-21/3 = 466/3
x = 233/3 = 77.6667
4+-3(7+2x)/5=-93.4
-3(7+2x)/5 = -97.4
7+2x = 487/3
2x = 487/3-21/3 = 466/3
x = 233/3 = 77.6667
2008-10-12 10:37 pm
4+-3(7+2x)/5+18.5=-74.9
-3(7+2x) = -21x-6x
-3(7+2x)/5 = (-21x-6x)/5
4+(-21-6x)/5+18.5=-74.9
-(6x/5)=-93.2
x=233/3 or 77.67
there
i hope it helps.
God Bless!
-3(7+2x) = -21x-6x
-3(7+2x)/5 = (-21x-6x)/5
4+(-21-6x)/5+18.5=-74.9
-(6x/5)=-93.2
x=233/3 or 77.67
there
i hope it helps.
God Bless!
2008-10-12 10:34 pm
4+ - 3(7+2x)/5+ 18.5=-74.9
4+(-21-6x)/5 +18.5= -74.9
20-21-6x+92.5=-374.5
-6x+91.5=-374.5
-6x=-466
x=77
4+(-21-6x)/5 +18.5= -74.9
20-21-6x+92.5=-374.5
-6x+91.5=-374.5
-6x=-466
x=77
2008-10-12 10:31 pm
4 + (-21 - 6x)/5 + 18.5 = -74.9
(-21 - 6x)/ 5 = -74.9 - 4 - 18.5
(-21 - 6x) / 5 = -97.4
-21 - 6x = -487
-6x = -466
x = -466 / -6 = 77 2/3?
(-21 - 6x)/ 5 = -74.9 - 4 - 18.5
(-21 - 6x) / 5 = -97.4
-21 - 6x = -487
-6x = -466
x = -466 / -6 = 77 2/3?
2008-10-12 10:31 pm
4+-3(7+2x)/5+18.5 = -74.9
4+(-21-6x)/5+18.5 = -74.9
4+-4.2-1.2x+18.5 = -74.9
18.3-1.2x = -74.9
18.3+74.9 = 1.2x
93.2 = 1.2x
x = 77.6
You are trying to work out x to make the left side of the equation equal to 74.9, if you multiply out the left hand side then you can get x on one side and numbers on the other (ax = b) this means you can work out what x equals (x = b/a)
4+(-21-6x)/5+18.5 = -74.9
4+-4.2-1.2x+18.5 = -74.9
18.3-1.2x = -74.9
18.3+74.9 = 1.2x
93.2 = 1.2x
x = 77.6
You are trying to work out x to make the left side of the equation equal to 74.9, if you multiply out the left hand side then you can get x on one side and numbers on the other (ax = b) this means you can work out what x equals (x = b/a)
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