Menu Close

Author: Tinku Tara

It-is-known-that-s-i-1-i-s-Prove-that-s-i-1-1-1-pi-i-s-where-pi-n-nth-prime-pi-1-2-pi-2-3-pi-3-5-

Question Number 3250 by Filup last updated on 08/Dec/15 $$\mathrm{It}\:\mathrm{is}\:\mathrm{known}\:\mathrm{that}: \\ $$$$\zeta\left({s}\right)=\underset{{i}=\mathrm{1}} {\overset{\infty} {\sum}}{i}^{−{s}} \\ $$$$ \\ $$$$\mathrm{Prove}\:\mathrm{that}: \\ $$$$\zeta\left({s}\right)=\underset{{i}=\mathrm{1}} {\overset{\infty} {\prod}}\left(\mathrm{1}−\frac{\mathrm{1}}{\pi\left({i}\right)^{{s}} }\right) \\ $$$$\mathrm{where}\:\pi\left({n}\right)={n}\mathrm{th}\:\mathrm{prime}…

A-lens-is-required-to-have-a-power-of-2-5-dioptres-in-air-the-convex-front-surface-has-a-radius-of-curvature-of-30cm-calculate-the-radius-of-curvature-of-the-rear-surface-

Question Number 134323 by aurpeyz last updated on 02/Mar/21 $${A}\:{lens}\:{is}\:{required}\:{to}\:{have}\:{a}\:{power}\:{of} \\ $$$$−\mathrm{2}.\mathrm{5}\:{dioptres}\:{in}\:{air}.\:{the}\:{convex} \\ $$$${front}\:{surface}\:{has}\:{a}\:{radius}\:{of}\:{curvature} \\ $$$${of}\:\mathrm{30}{cm}.\:{calculate}\:{the}\:{radius}\:{of}\:{curvature} \\ $$$${of}\:{the}\:{rear}\:{surface} \\ $$ Answered by ajfour last updated…

How-could-5-be-drawn-on-numbered-line-using-scale-and-compass-only-Exactly-5-not-its-decimal-approximation-

Question Number 3249 by Rasheed Soomro last updated on 08/Dec/15 $$\mathcal{H}{ow}\:{could}\:\sqrt{\mathrm{5}}\:\:{be}\:{drawn}\:{on}\:{numbered}\:{line}\:{using} \\ $$$${scale}\:{and}\:{compass}\:{only}?\:\left({Exactly}\:\sqrt{\mathrm{5}}\:{not}\:{its}\:{decimal}\:{approximation}.\right) \\ $$ Answered by prakash jain last updated on 08/Dec/15 $$\mathrm{For}\:\sqrt{\mathrm{5}} \\…

Let-d-n-be-the-determinant-of-the-n-n-matrix-whose-entries-from-left-to-right-and-then-from-top-to-bottom-are-cos-1-cos-2-cos-n-2-For-example-d-3-determinant-cos-1-cos-2-cos-3-

Question Number 68782 by Maclaurin Stickker last updated on 06/Oct/19 $$\mathrm{Let}\:{d}_{{n}} \:\mathrm{be}\:\mathrm{the}\:\mathrm{determinant}\:\mathrm{of}\:\mathrm{the}\:{n}×{n} \\ $$$$\mathrm{matrix}\:\mathrm{whose}\:\mathrm{entries},\:\mathrm{from}\:\mathrm{left}\:\mathrm{to}\:\mathrm{right} \\ $$$$\mathrm{and}\:\mathrm{then}\:\mathrm{from}\:\mathrm{top}\:\mathrm{to}\:\mathrm{bottom},\:\mathrm{are} \\ $$$${cos}\:\mathrm{1},\:{cos}\:\mathrm{2},\:…,\:{cos}\:{n}^{\mathrm{2}} .\:\left(\mathrm{For}\:\mathrm{example},\right. \\ $$$${d}_{\mathrm{3}} =\begin{vmatrix}{{cos}\:\mathrm{1}\:\:{cos}\:\mathrm{2}\:\:{cos}\:\mathrm{3}}\\{{cos}\:\mathrm{4}\:\:{cos}\:\mathrm{5}\:\:{cos}\:\mathrm{6}}\\{{cos}\:\mathrm{7}\:\:{cos}\:\mathrm{8}\:\:{cos}\:\mathrm{9}}\end{vmatrix}. \\ $$$$\mathrm{The}\:\mathrm{argument}\:\mathrm{of}\:{cos}\:\mathrm{is}\:\mathrm{always}\:\mathrm{in}\:\mathrm{radians} \\…