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how to solve absolute value equation?
How do I solve this absolute value equation. I think i'm getting confused with the 7-8 in the front.
7- 8 |7x - 4| = -12
8 Answers
- 9 years agoFavorite Answer
7 - 8* |7x-4| = -12
Take 7 over to the other side
- 8* |7x-4| = -19
Times both sides by -1
8* |7x-4| = 19
Divide both sides by 8
|7x-4| = 19/8
This basically means that 7x-4 is 19/8 from the origin. This means you need to solve the formular for the positive number that would make this true AND the negative number
Positive: 7x - 4 = 19/8
x = (19/8 +4)/7
x = 0.9107...
Now to get the other one set it equal to -19/8. This is because |-19/8| also equals 19/8
So..
7x - 4 = -19/8
x = (-19/8 + 4)/7
x = .232...
- 9 years ago
try to isolate the absolute value part and solve by using the two cases.
-8|7x - 4| = -19
|7x - 4| = 19/8
case 1 is where the answer is positive, so:
7x - 4 = 19/8
7x = 19/8 + 4
x = 51/56
case 2 is where the answer is negative, so:
7x - 4 = -19/8
7x = -19/8 + 4
x = 13/56
therefore, x = 51/56 or x = 13/56
- Anonymous9 years ago
7 - 8 |7x - 4| = -12
Subtract 7 from each side.
- 8 |7x - 4| = -19
Divide by -8.
|7x - 4| = 19/8
7x - 4 = -19/8 or 7x - 4 = 19/8
Add 4.
7x = 13/8 or 7x = 51/8
Divide by 7.
x = 13/56 or x = 51/56
- Anonymous9 years ago
there a 2 possibilties.....
|7x-4|= either -7x+4 or 7x-4 ok ...
now there will be two value of x :
7-8(-7x+4)= -12 7-8(7x-4)= -12
7+56x-32 = -12 7-56x+32 = -12
56x = 13 56x = 51
x=13/56 and x=51/56 :)
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- Anonymous9 years ago
setup:
-8⎢7x - 4⎥ = -19
⎢7x - 4⎥ = 19/8
solution 1:
7x - 4 = 19/8
7x = 51/8
x = 51/56
solution 2:
7x - 4 = -19/8
7x = 13/8
x = 13/56
Hope this helps!
Source(s): I took Algebra 2 last year. - Anonymous9 years ago
im not sure what an absolute value equation means, but to me it looks like calculus. you have to take the -8|7x-4| part and expand that. first you multiply -8 by 7x, then you multiply it by -4, which results in -56x+32. you then do 7-(-56x)+32=-12
7+56x+32=-12
56x=51
x=51/56
- Anonymous9 years ago
well, first you would multiply out the bracket to get 7-56x-32=-12 , then just solve the equation as you normally would
- Anonymous5 years ago
8+|x-1|=20 In any absolute value equation you MUST get rid of anything outside the absolute valu bars FIRST 8+|x-1|=20 -8...........-8 abs(x-1)=12.............since abs of 12 is 12 and the abs of -12 is 12 .......................you set what is in the absolute value bars equal to 12 and equal to -12 x-1=12...............x-1=-12............. add 1 to each side of both equations x=13..................x=-11