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

Mathematics

ScanSolve AI Answer

Answer

x=6x=6

Step-by-step solution

5 steps
  1. Combine logarithmic terms using the quotient rule.

    The logarithm property log⁡a−log⁡b=log⁡(a/b)\log a - \log b = \log(a/b) can be applied to both sides of the equation.

    log⁡(2x−112)=log⁡(3x)\log\left(\frac{2x-11}{2}\right) = \log\left(\frac{3}{x}\right)
  2. Equate the arguments of the logarithms.

    If log⁡A=log⁡B\log A = \log B, then A=BA = B.

    2x−112=3x\frac{2x-11}{2} = \frac{3}{x}
  3. Solve the algebraic equation.

    Multiply both sides by 2x2x to eliminate the denominators.

    x(2x−11)=2(3)x(2x-11) = 2(3) 2x2−11x=62x^2 - 11x = 6

    Rearrange the equation into standard quadratic form ax2+bx+c=0ax^2 + bx + c = 0.

    2x2−11x−6=02x^2 - 11x - 6 = 0
  4. Factor the quadratic equation.

    We look for two numbers that multiply to 2×−6=−122 \times -6 = -12 and add to −11-11. These numbers are −12-12 and 1.

    2x2−12x+x−6=02x^2 - 12x + x - 6 = 0

    Factor by grouping:

    2x(x−6)+1(x−6)=02x(x-6) + 1(x-6) = 0 (2x+1)(x−6)=0(2x+1)(x-6) = 0

    This gives two potential solutions for xx:

    2x+1=0  ⟹  2x=−1  ⟹  x=−122x+1 = 0 \implies 2x = -1 \implies x = -\frac{1}{2} x−6=0  ⟹  x=6x-6 = 0 \implies x = 6
  5. Check for valid solutions based on the domain of logarithms.

    The argument of a logarithm must be positive. From the original equation, we have two conditions:

    1. 2x−11>0  ⟹  2x>11  ⟹  x>5.52x-11 > 0 \implies 2x > 11 \implies x > 5.5
    2. x>0x > 0

    Let's check our potential solutions:

    • For x=−12x = -\frac{1}{2}: This value does not satisfy x>5.5x > 5.5 or x>0x > 0. Therefore, x=−12x = -\frac{1}{2} is an extraneous solution.
    • For x=6x = 6: This value satisfies both x>5.5x > 5.5 (since 6>5.56 > 5.5) and x>0x > 0. Therefore, x=6x=6 is the valid solution.
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