Math Problem Statement

Evaluate the logarithmic expressions: a) log₅ 5, b) log₇ 1, c) log₂ (1/4), d) log₇ √7, e) log_(2/3) (8/27), f) log₂ ³√2.

Solution

Let's evaluate each logarithm step by step:


a) log55\log_5 5

By the definition of a logarithm, logbb=1\log_b b = 1.
Thus, log55=1\log_5 5 = 1.


b) log71\log_7 1

By the property of logarithms, logb1=0\log_b 1 = 0 (for any b>0,b1b > 0, b \neq 1).
Thus, log71=0\log_7 1 = 0.


c) log2(14)\log_2 \left(\frac{1}{4}\right)

We rewrite 14\frac{1}{4} as 414^{-1}, and 4=224 = 2^2, so:
14=22.\frac{1}{4} = 2^{-2}. Using the property logb(an)=nlogba\log_b (a^n) = n \cdot \log_b a, we get:
log2(14)=log2(22)=2.\log_2 \left(\frac{1}{4}\right) = \log_2 \left(2^{-2}\right) = -2.


d) log77\log_7 \sqrt{7}

We rewrite 7\sqrt{7} as 71/27^{1/2}. Using logb(an)=nlogba\log_b (a^n) = n \cdot \log_b a, we get:
log77=log7(71/2)=12log77.\log_7 \sqrt{7} = \log_7 \left(7^{1/2}\right) = \frac{1}{2} \cdot \log_7 7. Since log77=1\log_7 7 = 1, we have:
log77=12.\log_7 \sqrt{7} = \frac{1}{2}.


e) log23(827)\log_{\frac{2}{3}} \left(\frac{8}{27}\right)

We rewrite 827\frac{8}{27} as (23)3\left(\frac{2}{3}\right)^3. Using the property logb(an)=nlogba\log_b (a^n) = n \cdot \log_b a, we get:
log23(827)=log23((23)3)=3.\log_{\frac{2}{3}} \left(\frac{8}{27}\right) = \log_{\frac{2}{3}} \left(\left(\frac{2}{3}\right)^3\right) = 3.


f) log223\log_2 \sqrt[3]{2}

We rewrite 23\sqrt[3]{2} as 21/32^{1/3}. Using logb(an)=nlogba\log_b (a^n) = n \cdot \log_b a, we get:
log223=log2(21/3)=13log22.\log_2 \sqrt[3]{2} = \log_2 \left(2^{1/3}\right) = \frac{1}{3} \cdot \log_2 2. Since log22=1\log_2 2 = 1, we have:
log223=13.\log_2 \sqrt[3]{2} = \frac{1}{3}.


Final Answers:

a) 11
b) 00
c) 2-2
d) 12\frac{1}{2}
e) 33
f) 13\frac{1}{3}


Would you like detailed explanations for any specific part? Let me know!

Here are 5 related questions to deepen your understanding:

  1. What is the value of logbbk\log_b b^k, and why does this property hold?
  2. How can we simplify logb(xy)\log_b \left(\frac{x}{y}\right) using logarithmic rules?
  3. What happens when the base bb of a logarithm is a fraction?
  4. How does the logarithmic property logb(an)\log_b (a^n) apply to roots and fractions?
  5. Why is logb1\log_b 1 always equal to 0, regardless of bb?

Tip: Always look for opportunities to rewrite numbers or fractions in terms of powers or roots of the base to simplify logarithms.

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Math Problem Analysis

Mathematical Concepts

Logarithms
Exponents
Properties of logarithms
Roots and fractional exponents

Formulas

log_b b = 1
log_b 1 = 0
log_b (a^n) = n * log_b a

Theorems

Definition of logarithms
Exponent rules

Suitable Grade Level

Grades 10-12