Math Problem Statement

solve the following

Solve the following math problems: 4. log_3(5x) - log_3(3x - 2) = -1 5. log_2(x^5) + log_x(32) = 10 6. 2(5^{x+1}) = 1 + 3/5^x 7. (3^x)(4^{2x+1}) = 6^{x+2}

Solution

Let's solve these one by one.

4. Solve for xx:

log3(5x)log3(3x2)=1\log_3(5x) - \log_3(3x - 2) = -1

Using the logarithmic identity loga(m)loga(n)=loga(mn)\log_a(m) - \log_a(n) = \log_a\left(\frac{m}{n}\right), the equation becomes: log3(5x3x2)=1\log_3\left(\frac{5x}{3x - 2}\right) = -1 This means: 5x3x2=31=13\frac{5x}{3x - 2} = 3^{-1} = \frac{1}{3} Now, cross-multiply: 5x=13(3x2)5x = \frac{1}{3}(3x - 2) 15x=3x215x = 3x - 2 15x3x=215x - 3x = -2 12x=212x = -2 x=212=16x = -\frac{2}{12} = -\frac{1}{6}

So, the solution is: x=16x = -\frac{1}{6}


5. Solve for xx:

log2(x5)+logx(32)=10\log_2(x^5) + \log_x(32) = 10

Using the logarithmic identity loga(bn)=nloga(b)\log_a(b^n) = n \log_a(b), the equation becomes: 5log2(x)+logx(32)=105 \log_2(x) + \log_x(32) = 10

Next, we know that logx(32)=1log2(x)\log_x(32) = \frac{1}{\log_2(x)}, because 32=2532 = 2^5, and by change of base formula: 5log2(x)+1log2(x)=105 \log_2(x) + \frac{1}{\log_2(x)} = 10 Let y=log2(x)y = \log_2(x). The equation becomes: 5y+1y=105y + \frac{1}{y} = 10 Multiply both sides by yy to get rid of the fraction: 5y2+1=10y5y^2 + 1 = 10y Rearrange this quadratic: 5y210y+1=05y^2 - 10y + 1 = 0 Solve this using the quadratic formula: y=(10)±(10)24(5)(1)2(5)y = \frac{-(-10) \pm \sqrt{(-10)^2 - 4(5)(1)}}{2(5)} y=10±1002010y = \frac{10 \pm \sqrt{100 - 20}}{10} y=10±8010y = \frac{10 \pm \sqrt{80}}{10} y=10±4510y = \frac{10 \pm 4\sqrt{5}}{10} y=1±255y = 1 \pm \frac{2\sqrt{5}}{5}

Since y=log2(x)y = \log_2(x), we can compute xx using x=2yx = 2^y.


6. Solve for xx:

2(5x+1)=1+35x2(5^{x+1}) = 1 + \frac{3}{5^x}

First, simplify: 25x+1=255x=105x2 \cdot 5^{x+1} = 2 \cdot 5 \cdot 5^x = 10 \cdot 5^x The equation becomes: 105x=1+35x10 \cdot 5^x = 1 + \frac{3}{5^x} Multiply both sides by 5x5^x to clear the fraction: 10(5x)2=5x+310 \cdot (5^x)^2 = 5^x + 3 Let y=5xy = 5^x. The equation becomes: 10y2=y+310y^2 = y + 3 Rearrange this into a quadratic equation: 10y2y3=010y^2 - y - 3 = 0 Solve using the quadratic formula: y=(1)±(1)24(10)(3)2(10)y = \frac{-(-1) \pm \sqrt{(-1)^2 - 4(10)(-3)}}{2(10)} y=1±1+12020y = \frac{1 \pm \sqrt{1 + 120}}{20} y=1±12120y = \frac{1 \pm \sqrt{121}}{20} y=1±1120y = \frac{1 \pm 11}{20} So, y=1220=35y = \frac{12}{20} = \frac{3}{5} or y=1020=12y = \frac{-10}{20} = -\frac{1}{2}.

Since y=5xy = 5^x, we solve 5x=355^x = \frac{3}{5}, which gives: x=log5(53)x = -\log_5\left(\frac{5}{3}\right)


7. Find the exact value of xx for the equation:

(3x)(42x+1)=6x+2(3^x)(4^{2x+1}) = 6^{x+2}

First, express everything in terms of powers of 2 and 3: 3x(22)2x+1=(23)x+23^x \cdot (2^2)^{2x+1} = (2 \cdot 3)^{x+2} Simplify the exponents: 3x24x+2=2x+23x+23^x \cdot 2^{4x+2} = 2^{x+2} \cdot 3^{x+2} Now, divide both sides by 3x3^x: 24x+2=2x+2322^{4x+2} = 2^{x+2} \cdot 3^2 24x+2=2x+292^{4x+2} = 2^{x+2} \cdot 9 Divide both sides by 2x+22^{x+2}: 23x=92^{3x} = 9 Take the logarithm base 2: 3x=log2(9)3x = \log_2(9) x=log2(9)3x = \frac{\log_2(9)}{3}

Now express the answer in the form lnalnb\frac{\ln a}{\ln b}: x=ln93ln2x = \frac{\ln 9}{3 \ln 2} x=ln323ln2=2ln33ln2x = \frac{\ln 3^2}{3 \ln 2} = \frac{2 \ln 3}{3 \ln 2}

So the exact value is: x=ln323ln2x = \frac{\ln 3^2}{3 \ln 2}


Let me know if you need further details on any of these solutions.

Related Questions:

  1. Can we apply the properties of logarithms to simplify expressions involving multiple logarithms?
  2. How do we solve quadratic equations involving logarithms?
  3. What are the logarithmic identities and how can they simplify equations?
  4. How does the quadratic formula help in solving transcendental equations?
  5. What is the change of base formula in logarithms, and when is it useful?

Tip: Always check if an equation can be simplified using logarithmic identities before proceeding to more complex steps.

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Math Problem Analysis

Mathematical Concepts

Logarithms
Exponents
Quadratic Equations
Change of Base Formula

Formulas

log_a(m) - log_a(n) = log_a(m/n)
log_a(b^n) = n log_a(b)
Quadratic Formula: y = (-b ± √(b^2 - 4ac)) / 2a
Change of Base Formula: log_a(b) = log_c(b) / log_c(a)

Theorems

Laws of Logarithms
Quadratic Equation Theorem
Change of Base Theorem

Suitable Grade Level

Grades 10-12