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If log 2 =x log 3=y and log 7 =z then th...

If log 2 =x log 3=y and log 7 =z then the value of `log(4xx root 3(63))`

A

(-2x+2/3y+1/3z)

B

2x+2/3y+1/3z

C

2x+2/3y-1/3z

D

2x-2/3 y+1/3 z

Text Solution

AI Generated Solution

The correct Answer is:
To solve the problem, we need to find the value of \( \log(4 \cdot \sqrt[3]{63}) \) given that \( \log 2 = x \), \( \log 3 = y \), and \( \log 7 = z \). ### Step 1: Rewrite the expression using logarithmic properties We can rewrite \( \log(4 \cdot \sqrt[3]{63}) \) using the property \( \log(m \cdot n) = \log m + \log n \): \[ \log(4 \cdot \sqrt[3]{63}) = \log 4 + \log(\sqrt[3]{63}) \] ### Step 2: Simplify \( \log 4 \) Since \( 4 = 2^2 \), we can use the property \( \log(m^n) = n \cdot \log m \): \[ \log 4 = \log(2^2) = 2 \log 2 = 2x \] ### Step 3: Simplify \( \log(\sqrt[3]{63}) \) The cube root can be expressed as a power: \[ \sqrt[3]{63} = 63^{1/3} \] Thus, we can write: \[ \log(\sqrt[3]{63}) = \log(63^{1/3}) = \frac{1}{3} \log 63 \] ### Step 4: Simplify \( \log 63 \) Next, we express \( 63 \) in terms of its prime factors: \[ 63 = 7 \cdot 9 = 7 \cdot 3^2 \] Using the property of logarithms: \[ \log 63 = \log(7 \cdot 3^2) = \log 7 + \log(3^2) = \log 7 + 2 \log 3 = z + 2y \] ### Step 5: Substitute back into the expression Now we can substitute \( \log 63 \) back into our expression for \( \log(\sqrt[3]{63}) \): \[ \log(\sqrt[3]{63}) = \frac{1}{3} \log 63 = \frac{1}{3}(z + 2y) = \frac{1}{3}z + \frac{2}{3}y \] ### Step 6: Combine the results Now we can combine \( \log 4 \) and \( \log(\sqrt[3]{63}) \): \[ \log(4 \cdot \sqrt[3]{63}) = 2x + \left(\frac{1}{3}z + \frac{2}{3}y\right) \] This simplifies to: \[ \log(4 \cdot \sqrt[3]{63}) = 2x + \frac{2}{3}y + \frac{1}{3}z \] ### Final Answer Thus, the value of \( \log(4 \cdot \sqrt[3]{63}) \) is: \[ \boxed{2x + \frac{2}{3}y + \frac{1}{3}z} \]
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