Harmonic Series and p-Series
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AP Calculus BC › Harmonic Series and p-Series
A camera stacks exposures summing $\sum_{n=1}^{\infty} \frac{1}{n^p}$; for which $p$ does the total exposure converge?
Converges for $p<1$
Converges for $p>1$
Converges for $p>0$
Converges for $p\le 1$
Converges for $p\ge 1$
Explanation
This question tests p-series convergence to determine when camera exposure stacking converges. The p-series $\sum_{n=1}^{\infty} \frac{1}{n^p}$ converges if and only if $p > 1$. For values $p \leq 1$, the series diverges because the individual terms don't decrease rapidly enough to produce convergence. The harmonic series (when $p = 1$) serves as the critical case and diverges. Choice A ($p \geq 1$) is incorrect because it includes the boundary case $p = 1$, which results in divergence. When working with p-series, always verify the exponent is strictly greater than 1 for convergence.
A lab totals measurement drift $\sum_{n=1}^{\infty} \frac{1}{n^p}$; for which $p$ does the series converge?
Converges for $p \geq 1$
Converges for $p \leq 1$
Converges for $p>0$
Converges for $p<1$
Converges for $p>1$
Explanation
This question tests p-series convergence to determine when lab measurement drift converges. The p-series $\sum_{n=1}^{\infty} \frac{1}{n^p}$ converges if and only if $p > 1$. For values $p \leq 1$, the series diverges because the individual terms don't decrease fast enough to produce convergence. The harmonic series (when $p = 1$) represents the critical dividing case and diverges. Choice A ($p \geq 1$) is tempting because it includes the boundary, but $p = 1$ results in divergence. When analyzing p-series, always confirm the exponent strictly exceeds 1 for convergence.
A telescope tracking error is $\sum_{n=1}^{\infty} \frac{1}{n^p}$; which choice correctly states when it converges?
Converges for $p<1$
Converges for $p\ge 1$
Converges for $p>0$
Converges for $p\le 1$
Converges for $p>1$
Explanation
This question tests p-series convergence to determine when telescope tracking error converges. The p-series $\sum_{n=1}^{\infty} \frac{1}{n^p}$ converges if and only if $p > 1$. For values $p \leq 1$, the series diverges because the individual terms don't decrease fast enough to ensure convergence. The harmonic series (when $p = 1$) represents the critical dividing case and diverges. Choice A ($p \geq 1$) is incorrect because it includes the boundary case $p = 1$, which results in divergence. When working with p-series, always verify that the exponent is strictly greater than 1 for convergence.
A machine learning update uses $\sum_{n=1}^{\infty} \frac{1}{n^p}$; for which $p$ is the total update finite?
Converges for $p>1$
Converges for $p>0$
Converges for $p\ge 1$
Converges for $p<1$
Converges for $p\le 1$
Explanation
This question tests p-series convergence to determine when machine learning update totals remain finite. The p-series $\sum_{n=1}^{\infty} \frac{1}{n^p}$ converges if and only if $p > 1$. When $p \leq 1$, the individual terms decrease too slowly for the infinite sum to converge to a finite value. The boundary case $p = 1$ produces the harmonic series, which diverges. Choice D ($p > 0$) might seem plausible since it ensures all terms are positive, but this incorrectly includes divergent cases. For p-series problems, remember that the exponent must strictly exceed 1 for convergence.
A computer graphics shader uses $\sum_{n=1}^{\infty} \frac{1}{n^p}$; for which $p$ does the series converge?
Converges for $p>0$
Converges for $p\ge 1$
Converges for $p\le 1$
Converges for $p>1$
Converges for $p<1$
Explanation
This question applies p-series convergence testing to determine when computer graphics shader series converge. The p-series $\sum_{n=1}^{\infty} \frac{1}{n^p}$ converges if and only if $p > 1$. For $p \leq 1$, the terms don't decrease fast enough for the infinite series to converge. At $p = 1$, we obtain the harmonic series which is known to diverge. Choice A ($p \geq 1$) is tempting because it includes the boundary case, but $p = 1$ leads to divergence. When analyzing p-series convergence, always confirm the exponent strictly exceeds 1.
A student tests $\sum_{n=1}^{\infty} \frac{1}{n^{9/8}}$; which statement about convergence is correct?
Converges because $p>1$.
Converges because $p=1$.
Converges because $p\le 1$.
Diverges because $p>1$.
Diverges because $p<1$.
Explanation
The student is testing the p-series $\sum_{n=1}^{\infty} \frac{1}{n^{9/8}}$ for convergence. Here, $p = 9/8 = 1.125$, which is greater than 1. The p-series test tells us that $\sum_{n=1}^{\infty} \frac{1}{n^p}$ converges when $p > 1$ and diverges when $p \leq 1$. Since $9/8 > 1$, this series converges. Choice A incorrectly claims divergence because $p < 1$, but $9/8 = 1.125 > 1$, demonstrating a misunderstanding of fraction comparison. For p-series with fractional exponents, check if the numerator exceeds the denominator—if yes, then $p > 1$ and the series converges.
In a model, decide whether $\sum_{n=1}^{\infty} \frac{1}{n^{4/3}}$ converges or diverges.
Converges because $p=1$.
Converges because $p>1$.
Diverges because $p<1$.
Converges because $p\le 1$.
Diverges because $p>1$.
Explanation
This model requires analyzing the p-series $\sum_{n=1}^{\infty} \frac{1}{n^{4/3}}$ for convergence. The exponent $p = 4/3 \approx 1.333$ is greater than 1. According to the p-series test, a series of the form $\sum_{n=1}^{\infty} \frac{1}{n^p}$ converges if and only if $p > 1$. Since $4/3 > 1$, this series converges. Choice C incorrectly states the series diverges because $p < 1$, but $4/3 = 1.333... > 1$, showing a fundamental error in comparing fractions. When testing p-series, convert fractions to decimals if needed to clearly see whether $p > 1$ for convergence.
For a savings model, determine whether $\sum_{n=1}^{\infty} \frac{1}{n^{8/7}}$ converges or diverges.
Diverges because $p<1$.
Converges because $p\le 1$.
Converges because $p=1$.
Diverges because $p>1$.
Converges because $p>1$.
Explanation
This savings model uses the p-series $\sum_{n=1}^{\infty} \frac{1}{n^{8/7}}$ where $p = 8/7 \approx 1.143$. The p-series test tells us that $\sum_{n=1}^{\infty} \frac{1}{n^p}$ converges if and only if $p > 1$. Since $8/7 > 1$, this series converges. Choice C incorrectly states divergence because $p < 1$, but $8/7 = 1.143... > 1$, demonstrating a misunderstanding of fraction values. For quick p-series testing, note that any fraction where the numerator exceeds the denominator gives $p > 1$, ensuring convergence.
A sensor records $\sum_{n=1}^{\infty} \frac{1}{n^{7/6}}$; does the series converge or diverge?
Converges because $p\le 1$.
Converges because $p>1$.
Diverges because $p<1$.
Diverges because $p>1$.
Diverges because $p=1$.
Explanation
This sensor recording problem involves testing the p-series $\sum_{n=1}^{\infty} \frac{1}{n^{7/6}}$. Here, $p = 7/6 \approx 1.167$, which is greater than 1. The p-series convergence test states that $\sum_{n=1}^{\infty} \frac{1}{n^p}$ converges when $p > 1$ and diverges when $p \leq 1$. Since $7/6 > 1$, this series converges. Choice A incorrectly claims divergence because $p = 1$, but $7/6 \neq 1$, revealing confusion about fraction evaluation. To quickly check p-series convergence, compare the exponent to 1: if the exponent exceeds 1, the series converges.
A telescope adds blur corrections $\sum_{n=1}^{\infty} \frac{1}{n^p}$; for which $p$ is the total correction finite?
Converges for $p>1$
Converges for $p\le 1$
Converges for $p<1$
Converges for $p\ge 1$
Converges for $p>0$
Explanation
This question tests p-series convergence to determine when telescope blur corrections remain finite. The p-series $\sum_{n=1}^{\infty} \frac{1}{n^p}$ converges if and only if $p > 1$. For $p \leq 1$, the series diverges because the individual terms don't decrease rapidly enough to ensure convergence. The boundary case $p = 1$ gives the harmonic series, which is a classic example of divergence. Choice A ($p > 0$) is incorrect because it includes many divergent cases like $p = 0.5$ or $p = 1$. When working with p-series, always confirm the exponent is strictly greater than 1 for convergence.