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Anonymous
Anonymous asked in Science & MathematicsMathematics · 1 decade ago

Solve for x.........?

sqrt(5x − 4) = (x/ 2 )+ 2

7 Answers

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  • ?
    Lv 6
    1 decade ago
    Favorite Answer

    5x - 4 ≥ 0

    x ≥ 4/5

    x/2 + 2 ≥ 0

    x/2 ≥ -2

    x ≥ -4

    => x ≥ 4/5

    5x - 4 = (x/2 + 2)^2

    5x - 4 = x^2/4 + 4 + 2x

    20x - 16 = x^2 + 16 + 8x

    x^2 - 12x + 32 = 0

    d = 144 - 4*32 = 16; sqrt d = 4

    x1 = (12+4)/2 = 8

    x2 = (12-4)/2 = 4

  • ?
    Lv 5
    1 decade ago

    2√(5x - 4) = x + 4

    The expression inside the radical must be positive --> x ≥ 4/5

    The RHS must be positive --> x ≥. -4

    --> x ≥ 4/5

    Square both sides::

    4(5x - 4) = (x + 4)^2

    20x - 16 = x^2 + 8x + 16

    x^2 - 12x + 32 = 0

    (x - 4)(x - 8) = 0

    x = 4, x = 8

    Another method:

    10&38730;(5x - 4) = 5x + 20

    Substitute t = √(5x - 4) (t ≥ 0)

    10t = t^2 + 24

    t^2 - 10t + 24 = 0

    (t - 4)(t - 6) = 0

    t = 4 --> 5x - 4 = 16 --> x = 4

    t = 6 --> 5x - 4 = 36 --> x = 8

    There are 2 solutions.

  • 1 decade ago

    the value of x is either 8 or 4

    this problem can be solved using the following steps:

    1.take the sqrt to the other side of the equation. <it becomes a sq>

    2.then simplify it

    3. next solve the quadratic eqation

    hope this helps!!! :)

  • ?
    Lv 7
    1 decade ago

    sqrt(5x − 4) = (x/2) + 2

    2sqrt(5x − 4) = (x + 4)

    2(5x - 4) = (x + 4)^2

    10x - 8 = x^2 + 8x + 16

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  • ?
    Lv 4
    1 decade ago

    I'll spare you the working out, and just tell you that my result was x = 4.

    The process was to expand and simplify both sides, until you're free of square roots and fractions. Then you transpose until you get the unknown (x) on one side on its own.

    Source(s): Advanced math classes for the last 4 years.
  • 1 decade ago

    Square both sides and expand the RHS and you can solve it already . Remember to check for extraneous solutions which do not satisfy the equation ,

  • Anonymous
    1 decade ago

    (5x-4)^2=x/2 +2

    25x^2-40x+16=x/2+2

    --------------------------------- x 2

    50x^2-80x+32=x+4

    50x^2-80x+32-x-4=0

    50x^2-81x+28=0

    50x^2-25x-56x+28=0

    25x(2x-1)-28(2x-1)=0

    (25x-28)(2x-1) =0

    25x-28 =o

    25x =28

    X1 = 28/25 = 1 3/25

    2x-1 =0

    2x =1

    X2 = 1/2

    Source(s): TOYS
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