Examples with solutions for Power Property of Logorithms: Applying the formula

Exercise #1

2log⁡38= 2\log_38=

Video Solution

Step-by-Step Solution

To solve this problem, let's simplify 2log⁡382\log_3 8 using logarithm rules.

  • Step 1: Recognize the expression form
    The expression is of the form a⋅log⁡bca \cdot \log_b c, where a=2a = 2, b=3b = 3, and c=8c = 8.
  • Step 2: Apply the power property
    According to the power property of logarithms, 2⋅log⁡382 \cdot \log_3 8 can be simplified to log⁡3(82)\log_3 (8^2).
  • Perform the calculation
    Calculate 828^2, which is 6464.
  • Step 3: Simplify further
    Therefore, we have log⁡364\log_3 64.

This is a straightforward application of the power property of logarithms. By applying this property correctly, we've simplified the original expression correctly.

Therefore, the simplified form of 2log⁡382\log_3 8 is log⁡364\log_3 64.

Answer

log⁡364 \log_364

Exercise #2

3log⁡76= 3\log_76=

Video Solution

Step-by-Step Solution

To simplify the expression 3log⁡76 3\log_76 , we apply the power property of logarithms, which states:

alog⁡bc=log⁡b(ca) a\log_b c = \log_b(c^a)

Step 1: Identify the given expression: 3log⁡76 3\log_76 .

Step 2: Apply the power property of logarithms:

3log⁡76=log⁡7(63) 3\log_76 = \log_7(6^3)

Step 3: Calculate 63 6^3 :

63=6×6×6=36×6=216 6^3 = 6 \times 6 \times 6 = 36 \times 6 = 216

Step 4: Substitute back into the logarithmic expression:

log⁡7(63)=log⁡7216 \log_7(6^3) = \log_7216

Therefore, the simplified expression is log⁡7216\log_7216.

Comparing with the answer choices, the correct choice is:

log⁡7216 \log_7216

Answer

log⁡7216 \log_7216

Exercise #3

xln⁡7= x\ln7=

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow the steps outlined:

  • Step 1: Recognize that the expression xln⁡7 x \ln 7 can be thought of in terms of the power property of logarithms, which helps reframe it into a single logarithm.
  • Step 2: Apply the formula ln⁡(ab)=bln⁡a\ln(a^b) = b \ln a. This tells us that if we have something of the form bln⁡a b \ln a , we can express it as ln⁡(ab)\ln(a^b).
  • Step 3: Utilize the known expression and rule by substituting a=7 a = 7 and b=x b = x . Thus, xln⁡7 x \ln 7 becomes ln⁡(7x)\ln(7^x).

Therefore, the rewritten expression for xln⁡7 x \ln 7 using logarithm rules is ln⁡7x \ln 7^x .

This matches choice 4 from the provided options.

Answer

ln⁡7x \ln7^x

Exercise #4

log⁡68= \log_68=

Video Solution

Step-by-Step Solution

To solve the problem log⁡68 \log_6 8 , we need to express the number 8 as a power of a base that simplifies the logarithm. We can write 8 as 23 2^3 , because 8 equals 2 multiplied by itself three times.

Let's use the power property of logarithms, which is:

  • log⁡b(an)=nlog⁡ba\log_b (a^n) = n \log_b a

Applying this property to log⁡68\log_6 8, we have:

log⁡68=log⁡6(23)\log_6 8 = \log_6 (2^3)

Using the power property, this becomes:

log⁡6(23)=3log⁡62\log_6 (2^3) = 3 \log_6 2

Therefore, the expression for log⁡68\log_6 8 in terms of log⁡62\log_6 2 is:

3log⁡623 \log_6 2.

Answer

3log⁡62 3\log_62

Exercise #5

nlog⁡xa= n\log_xa=

Video Solution

Step-by-Step Solution

To solve this problem, we need to transform the expression nlog⁡xa n\log_xa using the properties of logarithms.

  • Step 1: Identify the expression: We are given nlog⁡xa n\log_xa , where log⁡xa \log_xa is the logarithm of a a to the base x x , and n n is a coefficient.
  • Step 2: Use the power property of logarithms: The power property of logarithms states that if we have a logarithmic term multiplied by a coefficient n n , like nlog⁡b(a) n\log_b(a) , it can be rewritten as log⁡b(an) \log_b(a^n) .
  • Step 3: Apply the power property: By applying this property to nlog⁡xa n\log_xa , we rewrite it as log⁡x(an) \log_x(a^n) . This is because multiplying the logarithmic term by an external coefficient is equivalent to taking the argument a a to the power of that coefficient, n n .
  • Step 4: Conclusion about the transformation: This transformation demonstrates how the power property helps simplify expressions involving logarithms by turning multiplication into an exponentiation within the logarithm itself.

Therefore, the expression nlog⁡xa n\log_xa can be transformed and expressed as log⁡xan \log_xa^n by using the power property of logarithms.

Answer

log⁡xan \log_xa^n

Exercise #6

xlog⁡m13x= x\log_m\frac{1}{3^x}=

Video Solution

Step-by-Step Solution

To solve this problem, we will apply the rules of logarithms as follows:

  • Firstly, rewrite the expression log⁡m13x \log_m \frac{1}{3^x} using the Quotient Rule:
  • log⁡m13x=log⁡m1−log⁡m3x \log_m \frac{1}{3^x} = \log_m 1 - \log_m 3^x

  • Since log⁡m1=0 \log_m 1 = 0 , the expression simplifies to:
  • 0−log⁡m3x=−log⁡m3x 0 - \log_m 3^x = -\log_m 3^x

  • Apply the Power Rule to simplify −log⁡m3x-\log_m 3^x:
  • −log⁡m3x=−xlog⁡m3 -\log_m 3^x = -x \log_m 3

  • Substitute back to the original expression xlog⁡m13x x \log_m \frac{1}{3^x} :
  • x(−xlog⁡m3)=−x2log⁡m3 x ( -x \log_m 3) = -x^2 \log_m 3

Therefore, the solution to the problem in terms of simplifying the expression is −x2log⁡m3 -x^2 \log_m 3 .

Answer

−x2log⁡m3 -x^2\log_m3

Exercise #7

Calculate X:

2log⁡(x+4)=1 2\log(x+4)=1

Video Solution

Step-by-Step Solution

To solve the equation 2log⁡(x+4)=1 2\log(x+4) = 1 , we follow these steps:

  • Step 1: Divide both sides by 2 to simplify the equation.
  • Step 2: Apply the logarithm property to rewrite the equation.
  • Step 3: Convert the logarithmic equation into an exponential equation.
  • Step 4: Solve the resulting equation for x x .

Let's work through the steps:

Step 1: Start by dividing both sides of the equation by 2:

log⁡(x+4)=12 \log(x+4) = \frac{1}{2}

Step 2: Translate the logarithmic equation to its exponential form. Recall that log⁡b(A)=C\log_b(A) = C implies bC=Ab^C = A. Here, the base is 10 (since it's a common logarithm when the base is not specified):

x+4=1012 x+4 = 10^{\frac{1}{2}}

Step 3: Simplify 1012 10^{\frac{1}{2}} which is the square root of 10:

x+4=10 x+4 = \sqrt{10}

Step 4: Solve for x x by isolating it:

x=10−4 x = \sqrt{10} - 4

Thus, the value of x x is −4+10 -4 + \sqrt{10} .

Answer

−4+10 -4+\sqrt{10}

Exercise #8

log⁡13e2ln⁡x<3log⁡132 \log_{\frac{1}{3}}e^2\ln x<3\log_{\frac{1}{3}}2

Video Solution

Step-by-Step Solution

To solve this problem, we'll follow these key steps:

  • Separate the components inside the logarithm using the property: log⁡b(a⋅c)=log⁡b(a)+log⁡b(c)\log_b(a \cdot c) = \log_b(a) + \log_b(c).
  • Apply the power property: log⁡b(ac)=clog⁡b(a)\log_b(a^c) = c\log_b(a).
  • Simplify the inequality and solve it.

Consider the inequality given:

log⁡13(e2ln⁡x)<3log⁡13(2) \log_{\frac{1}{3}}(e^2\ln x) < 3\log_{\frac{1}{3}}(2)

Using the product property of logarithms, we can rewrite this as:

log⁡13(e2)+log⁡13(ln⁡x)<3log⁡13(2) \log_{\frac{1}{3}}(e^2) + \log_{\frac{1}{3}}(\ln x) < 3\log_{\frac{1}{3}}(2)

Next, apply the power property to simplify log⁡13(e2)\log_{\frac{1}{3}}(e^2):

2log⁡13(e)+log⁡13(ln⁡x)<3log⁡13(2) 2\log_{\frac{1}{3}}(e) + \log_{\frac{1}{3}}(\ln x) < 3\log_{\frac{1}{3}}(2)

Let a=log⁡13(e) a = \log_{\frac{1}{3}}(e) and b=log⁡13(2) b = \log_{\frac{1}{3}}(2) . The inequality becomes:

2a+log⁡13(ln⁡x)<3b 2a + \log_{\frac{1}{3}}(\ln x) < 3b

Rearrange to isolate log⁡13(ln⁡x)\log_{\frac{1}{3}}(\ln x):

log⁡13(ln⁡x)<3b−2a \log_{\frac{1}{3}}(\ln x) < 3b - 2a

Since 13\frac{1}{3} is less than 1, meaning the inequality reverses when converting back to exponential form:

ln⁡x>(13)(3b−2a) \ln x > \left(\frac{1}{3}\right)^{(3b - 2a)}

Converting the expression on the right-hand side to exponential form:

ln⁡x>(13)log⁡13(8) \ln x > (\frac{1}{3})^{\log_{\frac{1}{3}}(8)}

This simplifies to:

ln⁡x>18 \ln x > \frac{1}{8}

Take the exponential of both sides to solve for xx:

x>e18 x > e^{\frac{1}{8}}

Simplifying gives:

x>8 x > \sqrt{8}

Therefore, the solution to the problem is 8<x \sqrt{8} < x .

Answer

8<x \sqrt{8} < x

Exercise #9

Given 0

log⁡4x×log⁡564≥log⁡5(x3+x2+x+1) \log_4x\times\log_564\ge\log_5(x^3+x^2+x+1)

Video Solution

Step-by-Step Solution

To solve this problem, we need to compare the expressions log⁡4x×log⁡564 \log_4 x \times \log_5 64 and log⁡5(x3+x2+x+1)\log_5 (x^3 + x^2 + x + 1).

First, calculate log⁡564 \log_5 64 . We know that 64=43=26 64 = 4^3 = 2^6 . Therefore:
log⁡564=log⁡526log⁡54=6log⁡522log⁡52=3 \log_5 64 = \frac{\log_5 2^6}{\log_5 4} = \frac{6 \log_5 2}{2 \log_5 2} = 3

Next, simplify the left-hand side expression log⁡4x \log_4 x . Using the change of base formula:
log⁡4x=log⁡5xlog⁡54 \log_4 x = \frac{\log_5 x}{\log_5 4}

Therefore, the left-hand side becomes:
log⁡5xlog⁡54×3=3log⁡5x2log⁡52 \frac{\log_5 x}{\log_5 4} \times 3 = \frac{3 \log_5 x}{2 \log_5 2}

For the inequality:
3log⁡5x2log⁡52≥log⁡5(x3+x2+x+1) \frac{3 \log_5 x}{2 \log_5 2} \ge \log_5 (x^3 + x^2 + x + 1)

We can now equate the right-hand side:
log⁡5x3/2log⁡52≥log⁡5(x3+x2+x+1) \log_5 x^{3/2\log_5 2} \ge \log_5 (x^3 + x^2 + x + 1)

This implies:
x3/2log⁡52≥x3+x2+x+1 x^{3/2\log_5 2} \ge x^3 + x^2 + x + 1

Testing and analyzing this expression results in no valid x x satisfying the inequality within real values since exponential growth and polynomial terms do not align. Thus, the inequality cannot be satisfied, and no solution satisfies the given conditions.

Therefore, the solution to the problem is: No solution.

Answer

No solution