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Algebra Difficulty 3.0 Junior Find the answer

Given a=log0.32a = \log_{0.3}2, b=log20.3b = \log_{2}0.3, and c=0.20.3c = 0.2^{0.3}, determine the relationship between aa, bb, and cc.

Pick one

Solution

To solve this problem, we need to analyze the properties of logarithmic and exponential functions, using the monotonicity of these functions to compare the sizes of aa, bb, and cc.

First, let's analyze a=log0.32a = \log_{0.3}2. Note that log0.31=0\log_{0.3}1 = 0 and log0.310.3=1\log_{0.3}\frac{1}{0.3} = -1 since 0.31=10.30.3^{-1} = \frac{1}{0.3}. Given that log0.32\log_{0.3}2 is a logarithm of a number between 10.3\frac{1}{0.3} and 11, and considering the logarithm base is less than 1, which makes the logarithm function decreasing, we have:
-1 = \log_{0.3}\frac{1}{0.3} 1$, therefore $b<-1$ which implies: b < a. Finally, analyze $c = 0.2^{0.3}$. We know that $0.2^{0} = 1$ and that 0.3 is positive, so the value of $c$ must be between 0 and 1 (since exponential functions are monotonically increasing when the base is between 0 and 1): 0 < 0.2^{0.3} < 0.2^{0} = 1. Thus, $c$ is between $0$ and $1$. Bringing it all together we have: b < -1 < a < 0 < c < 1.Hence,therelationshipis: Hence, the relationship is: \boxed{b < a < c}.

Therefore, the correct answer is D.

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Source: NuminaMath-1.5, licensed Apache-2.0. Statement and solution reproduced as published; topic and difficulty added by this site.