Core Connections Algebra 2, 2013
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Core Connections Algebra 2, 2013 View details
3. Section 8.3
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Exercise 158 Page 423

Practice makes perfect
a To solve the given logarithmic equation, we will rewrite it in exponential form using the definition of a logarithm.
log_b x=y ⇔ x= b^y This definition tells us how to rewrite the logarithm equivalent of y in exponential form. The argument x is equal to b raised to the power of y. In the given equation, -2 is the exponent to which 3 must be raised to obtain 2x-1. Now, let's solve our equation.
2x-1 = 3^(-2)
Simplify right-hand side
2x-1 = 1/3^2
2x-1 = 1/9
2x = 1/9+1
2x = 1/9+9/9
2x = 10/9
x = 10/9/2
x = 10/2*9
x = 10/18
x = 5/9
We found that x= 59 is the answer to the given equation.
b To solve the given logarithmic equation, we will use the fact a logarithm is the inverse of an exponential function. Make sure that the base of the logarithm and the exponential expression are the same.

5^(log_5 ( x)) = 3 In our case, log_5 ( x) is the exponent to which 5 must be raised to result in the desired number. Because 5 raised to this exponent must be equal to 3, we have that x must be equal to 3. 5^(log_5 ( x)) = 3 ⇕ x = 3

c We want to solve an equation involving more than one logarithm. To do so we will use the Quotient Property of Logarithms.
log_b m - log_b n = log_b mn First, we can use the above property to isolate the variable from the logarithm. Then, we will write the right-hand side as a logarithm.
log_2(x) - log_2(3) = 4

log_2(m) - log_2(n)=log_2(m/n)

log_2(x/3) = 4

m=log_2(2^m)

log_2(x/3) = log_2 2^4
log_2(x/3) = log_2 16
Next, we will use the fact that if two equivalent logarithmic expressions have the same base, then the arguments must be equal. log_b x=log_b y ⇔ x= y Let's apply the above property to our equation.
log_2(x/3) = log_2 16

Equate arguments

x/3=16
x = 48
d
We want to use the Change of Base Formula to solve the given logarithmic equation. log_b m = log_c m/log_c b In the above formula m, b, and c are positive numbers, with b≠ 1 and c≠ 1. We will apply this formula to the expression on the left-hand side of the equation. log_3 ( 5) = log 5/log 3 Recall that if the base of a logarithm is not stated, it is 10. For example, log 5 = log_(10) 5. Logarithms with this base are called common logarithms, and can be found using a calculator.
log 5/log 3 = x
x = log 5/log 3

Calculate logarithm

x≈0.698970004/0.477121254
Simplify right-hand side
x≈0.698970004/0.477121254
x≈ 1.46497352...
x≈ 1.46