Math Problem Statement

Evaluate logarithmic expressions, determine why certain logarithms cannot be evaluated, and identify coordinates for logarithmic functions with specific y-values.

Solution

Here’s the solution to the questions from the uploaded image:


Question 9: Evaluate the logarithmic expressions

a) log24\log_2 4:
log24=x2x=4.\log_2 4 = x \quad \Rightarrow \quad 2^x = 4.
Since 22=42^2 = 4, the solution is: log24=2.\log_2 4 = 2.

b) log327\log_3 27:
log327=x3x=27.\log_3 27 = x \quad \Rightarrow \quad 3^x = 27.
Since 33=273^3 = 27, the solution is: log327=3.\log_3 27 = 3.

c) log464\log_4 64:
log464=x4x=64.\log_4 64 = x \quad \Rightarrow \quad 4^x = 64.
Since 43=644^3 = 64, the solution is: log464=3.\log_4 64 = 3.

d) log51\log_5 1:
log51=x5x=1.\log_5 1 = x \quad \Rightarrow \quad 5^x = 1.
Since 50=15^0 = 1, the solution is: log51=0.\log_5 1 = 0.

e) log2(12)\log_2 \left(\frac{1}{2}\right):
log2(12)=x2x=12.\log_2 \left(\frac{1}{2}\right) = x \quad \Rightarrow \quad 2^x = \frac{1}{2}.
Since 21=122^{-1} = \frac{1}{2}, the solution is: log2(12)=1.\log_2 \left(\frac{1}{2}\right) = -1.

f) log33\log_3 \sqrt{3}:
log33=x3x=3.\log_3 \sqrt{3} = x \quad \Rightarrow \quad 3^x = \sqrt{3}.
Since 3=31/2\sqrt{3} = 3^{1/2}, the solution is: log33=12.\log_3 \sqrt{3} = \frac{1}{2}.


Question 10: Why can log3(9)\log_3(-9) not be evaluated?

The logarithm of a negative number is undefined in the real number system because the base raised to any real power cannot result in a negative value.
For example:
3x9for any real x.3^x \neq -9 \quad \text{for any real } x.
Thus, log3(9)\log_3(-9) is undefined.


Question 11: Find coordinates with yy-values 2,1,0,1,2-2, -1, 0, 1, 2 for each function

a) y=log2xy = \log_2 x:

To find xx values for y=2,1,0,1,2y = -2, -1, 0, 1, 2:
x=2y.x = 2^y.

yyx=2yx = 2^yCoordinates (x,y)(x, y)
-222=142^{-2} = \frac{1}{4}(14,2)\left(\frac{1}{4}, -2\right)
-121=122^{-1} = \frac{1}{2}(12,1)\left(\frac{1}{2}, -1\right)
020=12^0 = 1(1,0)(1, 0)
121=22^1 = 2(2,1)(2, 1)
222=42^2 = 4(4,2)(4, 2)

b) y=log10xy = \log_{10} x:

To find xx values for y=2,1,0,1,2y = -2, -1, 0, 1, 2:
x=10y.x = 10^y.

yyx=10yx = 10^yCoordinates (x,y)(x, y)
-2102=0.0110^{-2} = 0.01(0.01,2)(0.01, -2)
-1101=0.110^{-1} = 0.1(0.1,1)(0.1, -1)
0100=110^0 = 1(1,0)(1, 0)
1101=1010^1 = 10(10,1)(10, 1)
2102=10010^2 = 100(100,2)(100, 2)

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Expanding Questions:

  1. What is the difference between real and complex logarithms?
  2. How do logarithmic functions behave asymptotically as xx \to \infty?
  3. What are the properties of logarithmic scales, e.g., in sound intensity or pH levels?
  4. How can logarithmic functions be used to solve exponential equations?
  5. What is the significance of the change-of-base formula in logarithms?

Tip:

Logarithms are the inverse of exponential functions. Understanding their relationship helps in solving problems that involve both functions effectively.

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Math Problem Analysis

Mathematical Concepts

Logarithms
Exponential functions
Properties of logarithms

Formulas

log_b(x) = y ⇔ b^y = x
x = b^y to find coordinates for logarithmic functions

Theorems

Definition of logarithms
Properties of exponents
Domain of logarithmic functions

Suitable Grade Level

Grades 9-12