Math Problem Statement

Solve for all values of x: log_6(2x^2 - 3) - log_6(3x + 2) = 0

Solution

The equation you've provided is:

log6(2x23)log6(3x+2)=0\log_6(2x^2 - 3) - \log_6(3x + 2) = 0

Step-by-step solution:

  1. Use the logarithmic property: The property logb(a)logb(c)=logb(ac)\log_b(a) - \log_b(c) = \log_b\left(\frac{a}{c}\right) allows us to combine the logarithms on the left-hand side: log6(2x233x+2)=0\log_6\left(\frac{2x^2 - 3}{3x + 2}\right) = 0

  2. Rewrite the equation: By the definition of logarithms, logb(a)=0\log_b(a) = 0 means that a=1a = 1 (since b0=1b^0 = 1). Thus, we can set the argument of the logarithm equal to 1: 2x233x+2=1\frac{2x^2 - 3}{3x + 2} = 1

  3. Solve the rational equation: Multiply both sides by 3x+23x + 2 to eliminate the denominator: 2x23=3x+22x^2 - 3 = 3x + 2 Rearrange the equation: 2x23x5=02x^2 - 3x - 5 = 0

  4. Solve the quadratic equation: Use the quadratic formula to solve 2x23x5=02x^2 - 3x - 5 = 0: x=(3)±(3)24(2)(5)2(2)x = \frac{-(-3) \pm \sqrt{(-3)^2 - 4(2)(-5)}}{2(2)} Simplify: x=3±9+404x = \frac{3 \pm \sqrt{9 + 40}}{4} x=3±494x = \frac{3 \pm \sqrt{49}}{4} x=3±74x = \frac{3 \pm 7}{4}

    This gives two solutions: x=3+74=104=2.5x = \frac{3 + 7}{4} = \frac{10}{4} = 2.5 x=374=44=1x = \frac{3 - 7}{4} = \frac{-4}{4} = -1

  5. Check for extraneous solutions: Since logarithms are only defined for positive arguments, we must check that both solutions keep the arguments of the original logarithms positive:

    • For x=2.5x = 2.5: 2(2.5)23=12.53=9.5>02(2.5)^2 - 3 = 12.5 - 3 = 9.5 > 0 3(2.5)+2=7.5+2=9.5>03(2.5) + 2 = 7.5 + 2 = 9.5 > 0 Both arguments are positive, so x=2.5x = 2.5 is valid.

    • For x=1x = -1: 2(1)23=23=1<02(-1)^2 - 3 = 2 - 3 = -1 < 0 This makes the first logarithmic argument negative, which is invalid. So, x=1x = -1 is not a valid solution.

Final Answer:

The only solution is x=2.5x = 2.5.

Would you like further details or have any questions? Here are some related problems you might find interesting:

  1. Solve log3(x24)log3(x2)=1\log_3(x^2 - 4) - \log_3(x - 2) = 1.
  2. Solve log2(5x+6)log2(x)=3\log_2(5x + 6) - \log_2(x) = 3.
  3. Solve log10(2x+1)=2\log_{10}(2x + 1) = 2.
  4. Solve log7(x+3)+log7(x1)=1\log_7(x + 3) + \log_7(x - 1) = 1.
  5. Solve log5(x22x)log5(x3)=0\log_5(x^2 - 2x) - \log_5(x - 3) = 0.

Tip: Always check the domain of logarithmic equations to ensure that the arguments are positive!

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Math Problem Analysis

Mathematical Concepts

Logarithms
Algebra
Quadratic Equations

Formulas

log_b(a) - log_b(c) = log_b(a/c)
log_b(a) = 0 means a = 1
Quadratic formula: x = [-b ± sqrt(b^2 - 4ac)] / 2a

Theorems

Logarithmic properties
Quadratic formula

Suitable Grade Level

Grades 9-12