Math Problem Statement

Log 8 + Log 16 - 4 Log 2 (Base 2), Log 16 (Base 4), and evaluations without using tables such as (0.64)^1/2, (25/9)^3/2, (0.36)^1/2, and (125/27)^-2/3.

Solution

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  1. Expression 1:
    log28+log2164log22\log_2 8 + \log_2 16 - 4 \log_2 2

  2. Expression 2:
    log416\log_4 16

  3. Expression 3: Without using tables, evaluate:
    (i) (0.64)1/2(0.64)^{1/2}
    (ii) (259)3/2\left(\frac{25}{9}\right)^{3/2}
    (iii) (0.36)1/2(0.36)^{1/2}
    (iv) (12527)2/3\left(\frac{125}{27}\right)^{-2/3}


Solution

1. Solving log28+log2164log22\log_2 8 + \log_2 16 - 4\log_2 2:

  • Recall the property: logb(xy)=logbx+logby\log_b(x \cdot y) = \log_b x + \log_b y, and logb(xn)=nlogbx\log_b(x^n) = n \cdot \log_b x.
  • Breakdown:
    log28=log2(23)=3,log216=log2(24)=4,and 4log22=41=4.\log_2 8 = \log_2(2^3) = 3, \quad \log_2 16 = \log_2(2^4) = 4, \quad \text{and } 4 \log_2 2 = 4 \cdot 1 = 4.
  • Substitute:
    log28+log2164log22=3+44=3.\log_2 8 + \log_2 16 - 4 \log_2 2 = 3 + 4 - 4 = 3.
  • Answer: 33.

2. Solving log416\log_4 16:

  • Convert to base 4:
    log416=log4(42)=2log44=21=2.\log_4 16 = \log_4(4^2) = 2 \cdot \log_4 4 = 2 \cdot 1 = 2.
  • Answer: 22.

3. Evaluations Without Using Tables

(i) (0.64)1/2(0.64)^{1/2}:
(0.64)1/2=0.64=0.8.(0.64)^{1/2} = \sqrt{0.64} = 0.8.
Answer: 0.80.8.


(ii) (259)3/2\left(\frac{25}{9}\right)^{3/2}:

  • Apply the exponent rule:
    (259)3/2=(259)3=(259)3=(53)3=12527.\left(\frac{25}{9}\right)^{3/2} = \left(\sqrt{\frac{25}{9}}\right)^3 = \left(\frac{\sqrt{25}}{\sqrt{9}}\right)^3 = \left(\frac{5}{3}\right)^3 = \frac{125}{27}.
  • Answer: 12527\frac{125}{27}.

(iii) (0.36)1/2(0.36)^{1/2}:
(0.36)1/2=0.36=0.6.(0.36)^{1/2} = \sqrt{0.36} = 0.6.
Answer: 0.60.6.


(iv) (12527)2/3\left(\frac{125}{27}\right)^{-2/3}:

  • Apply the exponent rule:
    [ \left(\frac{125}{27}\right)^{-2/3} = \frac{1}{\left(\frac{125}{27}\right)^{2/3}} = \frac{1}{\left(\frac{\sqrt[3]{125}}{\sqrt[3]{27}}\right)^2}. ]
  • Simplify cube roots:
    [ \sqrt[3]{125} = 5, \quad \sqrt[3]{27} = 3 \quad \implies \left(\frac{\sqrt[3]{125}}{\sqrt[3]{27}}\right)^2 = \left(\frac{5}{3}\right)^2 = \frac{25}{9}. ]
  • Reciprocal:
    (12527)2/3=1259=925.\left(\frac{125}{27}\right)^{-2/3} = \frac{1}{\frac{25}{9}} = \frac{9}{25}.
  • Answer: 925\frac{9}{25}.

Summary of Answers:

  1. 33
  2. 22
  3. (i) 0.80.8, (ii) 12527\frac{125}{27}, (iii) 0.60.6, (iv) 925\frac{9}{25}.

Would you like more details or have any specific questions? Here are 5 related questions to explore:

  1. What are other properties of logarithms that are useful for simplifications?
  2. How do fractional exponents relate to roots in mathematics?
  3. How can negative exponents be interpreted with fractions?
  4. How do we approach solving logarithms with bases other than 10 or 2?
  5. Can you explain why cube roots are used in 12527\frac{125}{27} specifically?

Tip: When working with fractional exponents, remember xm/nx^{m/n} means the nn-th root of xmx^m.

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Math Problem Analysis

Mathematical Concepts

Logarithms
Exponents
Roots
Fractional Exponents

Formulas

log_b(x * y) = log_b(x) + log_b(y)
log_b(x^n) = n * log_b(x)
x^(m/n) = (nth root of x)^m

Theorems

Logarithmic product rule
Logarithmic power rule
Exponentiation and roots relationship

Suitable Grade Level

Grades 9-12