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f-x-y-f-x-1-y-y-x-gt-0-f-x-y-y-1-x-x-0-y-gt-0-xy-x-0-y-0-f-5-7-f-6-9-

Question Number 3793 by 123456 last updated on 21/Dec/15 $${f}\left({x},{y}\right)=\begin{cases}{{f}\left({x}−\mathrm{1},{y}\right)+{y}}&{{x}>\mathrm{0}}\\{{f}\left({x}+{y},{y}−\mathrm{1}\right)+{x}}&{{x}\leqslant\mathrm{0}\wedge{y}>\mathrm{0}}\\{{xy}}&{{x}\leqslant\mathrm{0}\wedge{y}\leqslant\mathrm{0}}\end{cases} \\ $$$${f}\left(\mathrm{5},\mathrm{7}\right)=? \\ $$$${f}\left(\mathrm{6},\mathrm{9}\right)=?? \\ $$ Commented by prakash jain last updated on 21/Dec/15 $${y}>\mathrm{0}…

f-nx-f-x-n-f-x-f-0-0-f-x-

Question Number 3789 by 123456 last updated on 21/Dec/15 $${f}\left({nx}\right)={f}\left({x}+{n}\right)−{f}\left({x}\right) \\ $$$${f}\left(\mathrm{0}\right)=\mathrm{0} \\ $$$${f}\left({x}\right)=? \\ $$ Commented by Rasheed Soomro last updated on 21/Dec/15 $${f}\left({nx}\right)={f}\left({x}+{n}\right)−{f}\left({x}\right)…

if-5-x-y-40-are-in-GP-find-x-and-y-

Question Number 69314 by mezihloic last updated on 22/Sep/19 $${if}\:\mathrm{5}\:{x}\:{y}\:\mathrm{40}\:{are}\:{in}\:{GP}\:.{find}\:{x}\:{and}\:{y} \\ $$ Commented by Rasheed.Sindhi last updated on 22/Sep/19 $$\frac{{x}}{\mathrm{5}}=\frac{{y}}{{x}}=\frac{\mathrm{40}}{{y}} \\ $$$${xy}=\mathrm{200} \\ $$$${x}^{\mathrm{2}} =\mathrm{5}{y}\Rightarrow{x}^{\mathrm{2}}…

show-that-c-a-c-a-

Question Number 69247 by Rio Michael last updated on 21/Sep/19 $${show}\:{that}\: \\ $$$$\:{c}\mid{a}\:\Leftrightarrow\:−{c}\mid{a}. \\ $$ Commented by kaivan.ahmadi last updated on 22/Sep/19 $${c}\mid{a}\Rightarrow{a}={cx};\:\exists{x}\in\mathbb{Z} \\ $$$$\Rightarrow{a}=−{c}\left(−{x}\right)…

Use-Residus-theorem-to-prove-that-a-gt-0-n-0-1-n-2-a-2-1-2-pi-ash-pia-1-a-2-and-n-0-1-n-n-2-a-2-1-2-pi-a-th-pia-1-a-2-Assume

Question Number 69236 by ~ À ® @ 237 ~ last updated on 21/Sep/19 $${Use}\:\:{Residus}\:{theorem}\:{to}\:{prove}\:{that}\:\forall\:{a}>\mathrm{0}\:\:\underset{{n}=\mathrm{0}} {\overset{\infty} {\sum}}\:\frac{\mathrm{1}}{\:{n}^{\mathrm{2}} +{a}^{\mathrm{2}} }\:=\:\frac{\mathrm{1}}{\mathrm{2}}\left(\frac{\pi}{{ash}\left(\pi{a}\right)}\:\:\:−\frac{\mathrm{1}}{{a}^{\mathrm{2}} }\right) \\ $$$${and}\:\:\:\:\:\:\underset{{n}=\mathrm{0}} {\overset{\infty} {\sum}}\:\frac{\left(−\mathrm{1}\right)^{{n}} }{{n}^{\mathrm{2}}…

help-please-A-river-is-5m-wide-and-flows-at-3-0ms-1-A-man-can-swim-at-2-0ms-1-in-still-water-if-he-sets-off-at-an-angle-of-90-to-the-bank-calculate-a-the-mans-time-and-velocity-b-his-di

Question Number 69207 by Rio Michael last updated on 21/Sep/19 $${help}\:{please}. \\ $$$$ \\ $$$${A}\:{river}\:{is}\:\mathrm{5}{m}\:{wide}\:{and}\:{flows}\:{at}\:\mathrm{3}.\mathrm{0}{ms}^{−\mathrm{1}} .\:{A}\:{man}\:{can}\:{swim}\:{at}\:\mathrm{2}.\mathrm{0}{ms}^{−\mathrm{1}} \\ $$$${in}\:{still}\:{water}.\:{if}\:{he}\:{sets}\:{off}\:{at}\:{an}\:{angle}\:{of}\:\mathrm{90}°\:{to}\:{the}\:{bank} \\ $$$${calculate} \\ $$$$\left.{a}\right)\:{the}\:{mans}\:{time}\:{and}\:{velocity} \\ $$$$\left.{b}\right)\:{his}\:{distance}\:{downstream}\:{from}\:{the}\:{starting}\:{point}\:{till} \\…

f-x-p-q-x-p-q-p-Z-q-Z-q-0-p-q-1-x-10x-overtise-does-f-is-continuous-

Question Number 3655 by 123456 last updated on 17/Dec/15 $${f}\left({x}\right)=\begin{cases}{{p}+{q}}&{{x}=\frac{{p}}{{q}},{p}\in\mathbb{Z},{q}\in\mathbb{Z},{q}\neq\mathrm{0},\left({p},{q}\right)=\mathrm{1}}\\{\lfloor{x}\rfloor+\lfloor\mathrm{10}{x}\rfloor}&{\mathrm{overtise}}\end{cases} \\ $$$$\mathrm{does}\:{f}\:\mathrm{is}\:\mathrm{continuous}? \\ $$ Commented by prakash jain last updated on 18/Dec/15 $${choose}\:{p}\notin\mathbb{Q},\:\mathrm{say}\:{p}=\pi \\ $$$$\mathrm{Checking}\:\mathrm{for}\:\mathrm{definition}…