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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

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  • 9 years ago
    Favorite 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

  • Anonymous
    9 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

  • Anonymous
    9 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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  • Anonymous
    9 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.
  • Anonymous
    9 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

  • Anonymous
    9 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

  • Anonymous
    5 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

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