Find the value of x that satisfies the equation Log(2x−11)−log2=log3−log x

Mathematics

ScanSolve AI Answer

Answer

6

Step-by-step solution

7 steps
  1. Use the logarithm property log⁡a−log⁡b=log⁡ab\log a - \log b = \log \frac{a}{b} to combine terms on both sides of the equation.

    log⁡(2x−112)=log⁡(3x)\log \left( \frac{2x-11}{2} \right) = \log \left( \frac{3}{x} \right)
  2. Since the logarithms on both sides are equal, their arguments must be equal.

    2x−112=3x\frac{2x-11}{2} = \frac{3}{x}
  3. Cross-multiply to eliminate the denominators.

    x(2x−11)=2(3)x(2x-11) = 2(3) 2x2−11x=62x^2 - 11x = 6
  4. Rearrange the equation into a quadratic form ax2+bx+c=0ax^2 + bx + c = 0.

    2x2−11x−6=02x^2 - 11x - 6 = 0
  5. Solve the quadratic equation using the quadratic formula x=−b±b2−4ac2ax = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}.

    Here, a=2a=2, b=−11b=-11, and c=−6c=-6.

    x=−(−11)±(−11)2−4(2)(−6)2(2)x = \frac{-(-11) \pm \sqrt{(-11)^2 - 4(2)(-6)}}{2(2)} x=11±121+484x = \frac{11 \pm \sqrt{121 + 48}}{4} x=11±1694x = \frac{11 \pm \sqrt{169}}{4} x=11±134x = \frac{11 \pm 13}{4}
  6. Calculate the two possible values for x.

    x1=11+134=244=6x_1 = \frac{11 + 13}{4} = \frac{24}{4} = 6 x2=11−134=−24=−12x_2 = \frac{11 - 13}{4} = \frac{-2}{4} = -\frac{1}{2}
  7. Check for extraneous solutions.

    The argument of a logarithm must be positive.
    For x=6x=6:
    2x−11=2(6)−11=12−11=1>02x-11 = 2(6)-11 = 12-11 = 1 > 0
    x=6>0x = 6 > 0
    This solution is valid.

    For x=−12x=-\frac{1}{2}:
    2x−11=2(−12)−11=−1−11=−12<02x-11 = 2(-\frac{1}{2})-11 = -1-11 = -12 < 0
    The argument of the logarithm cannot be negative. This solution is extraneous.

    The only valid solution is x=6x=6.

    66
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