1. Problem: Solve the inequality $$\log_{\frac{1}{5}}(x - 5) > -2$$.
2. Formula and rules: For logarithmic inequalities with base $a$ where $0 < a < 1$, the inequality direction reverses when removing the log. Also, the argument of the log must be positive: $$x - 5 > 0 \Rightarrow x > 5$$.
3. Solve the inequality:
$$\log_{\frac{1}{5}}(x - 5) > -2 \Rightarrow x - 5 < \left(\frac{1}{5}\right)^{-2}$$ because base $\frac{1}{5} < 1$ reverses inequality.
4. Calculate the right side:
$$\left(\frac{1}{5}\right)^{-2} = 5^2 = 25$$.
5. So,
$$x - 5 < 25 \Rightarrow x < 30$$.
6. Combine domain and inequality:
$$5 < x < 30$$.
7. Final answer: Interval notation is $$]5; 30[\,$$ which corresponds to option C.
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1. Problem: Solve $$\log_{\frac{1}{9}}(x + 3) > -0.5$$.
2. Domain: $$x + 3 > 0 \Rightarrow x > -3$$.
3. Since base $\frac{1}{9} < 1$, inequality reverses:
$$x + 3 < \left(\frac{1}{9}\right)^{-0.5}$$.
4. Calculate right side:
$$\left(\frac{1}{9}\right)^{-0.5} = 9^{0.5} = 3$$.
5. So,
$$x + 3 < 3 \Rightarrow x < 0$$.
6. Combine domain and inequality:
$$-3 < x < 0$$.
7. Final answer: $$]-3; 0[\,$$ which is option C.
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1. Problem: Solve $$\log_{\frac{1}{4}}(x - 3) > 1.5$$.
2. Domain: $$x - 3 > 0 \Rightarrow x > 3$$.
3. Base $\frac{1}{4} < 1$ reverses inequality:
$$x - 3 < \left(\frac{1}{4}\right)^{1.5}$$.
4. Calculate right side:
$$\left(\frac{1}{4}\right)^{1.5} = 4^{-1.5} = \frac{1}{4^{1.5}} = \frac{1}{8} = 0.125$$.
5. So,
$$x - 3 < 0.125 \Rightarrow x < 3.125$$.
6. Combine domain and inequality:
$$3 < x < 3.125$$.
7. Final answer: $$]3; 3.125[\,$$ which is option E.
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1. Problem: Solve $$\log_{\frac{1}{3}}(x - 5) > -3$$.
2. Domain: $$x - 5 > 0 \Rightarrow x > 5$$.
3. Base $\frac{1}{3} < 1$ reverses inequality:
$$x - 5 < \left(\frac{1}{3}\right)^{-3}$$.
4. Calculate right side:
$$\left(\frac{1}{3}\right)^{-3} = 3^3 = 27$$.
5. So,
$$x - 5 < 27 \Rightarrow x < 32$$.
6. Combine domain and inequality:
$$5 < x < 32$$.
7. Final answer: $$]5; 32[\,$$ which is option D.
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1. Problem: Solve $$\log_{\frac{1}{2}}(x + 3) > -2$$.
2. Domain: $$x + 3 > 0 \Rightarrow x > -3$$.
3. Base $\frac{1}{2} < 1$ reverses inequality:
$$x + 3 < \left(\frac{1}{2}\right)^{-2}$$.
4. Calculate right side:
$$\left(\frac{1}{2}\right)^{-2} = 2^2 = 4$$.
5. So,
$$x + 3 < 4 \Rightarrow x < 1$$.
6. Combine domain and inequality:
$$-3 < x < 1$$.
7. Final answer: $$]-3; 1[\,$$ which is option C.
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1. Problem: Solve $$\log_{\frac{1}{3}}(x - 2) > -1$$.
2. Domain: $$x - 2 > 0 \Rightarrow x > 2$$.
3. Base $\frac{1}{3} < 1$ reverses inequality:
$$x - 2 < \left(\frac{1}{3}\right)^{-1}$$.
4. Calculate right side:
$$\left(\frac{1}{3}\right)^{-1} = 3$$.
5. So,
$$x - 2 < 3 \Rightarrow x < 5$$.
6. Combine domain and inequality:
$$2 < x < 5$$.
7. Final answer: $$]2; 5[\,$$ which is option B.
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1. Problem: Solve $$\log_{\frac{1}{2}}(x - 5) > -2$$.
2. Domain: $$x - 5 > 0 \Rightarrow x > 5$$.
3. Base $\frac{1}{2} < 1$ reverses inequality:
$$x - 5 < \left(\frac{1}{2}\right)^{-2}$$.
4. Calculate right side:
$$\left(\frac{1}{2}\right)^{-2} = 2^2 = 4$$.
5. So,
$$x - 5 < 4 \Rightarrow x < 9$$.
6. Combine domain and inequality:
$$5 < x < 9$$.
7. Final answer: $$]5; 9[\,$$ which is option D.
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1. Problem: Solve $$\log_{3}(x + 20) < 3$$.
2. Domain: $$x + 20 > 0 \Rightarrow x > -20$$.
3. Base $3 > 1$ keeps inequality direction:
$$x + 20 < 3^3$$.
4. Calculate right side:
$$3^3 = 27$$.
5. So,
$$x < 7$$.
6. Combine domain and inequality:
$$-20 < x < 7$$.
7. Final answer: $$]-20; 7[\,$$ which is option D.
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1. Problem: Solve $$\log_{5}(x + 13) < 2$$.
2. Domain: $$x + 13 > 0 \Rightarrow x > -13$$.
3. Base $5 > 1$ keeps inequality direction:
$$x + 13 < 5^2$$.
4. Calculate right side:
$$5^2 = 25$$.
5. So,
$$x < 12$$.
6. Combine domain and inequality:
$$-13 < x < 12$$.
7. Final answer: $$]-13; 12[\,$$ which is option E.
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1. Problem: Solve $$\log_{\frac{1}{8}}(x - 7) > -\frac{2}{3}$$.
2. Domain: $$x - 7 > 0 \Rightarrow x > 7$$.
3. Base $\frac{1}{8} < 1$ reverses inequality:
$$x - 7 < \left(\frac{1}{8}\right)^{-\frac{2}{3}}$$.
4. Calculate right side:
$$\left(\frac{1}{8}\right)^{-\frac{2}{3}} = 8^{\frac{2}{3}} = (2^3)^{\frac{2}{3}} = 2^2 = 4$$.
5. So,
$$x - 7 < 4 \Rightarrow x < 11$$.
6. Combine domain and inequality:
$$7 < x < 11$$.
7. Final answer: $$]7; 11[\,$$ which is option C.
Logarithmic Inequalities 8D3Cab
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