Question Number 1899 by Yozzy last updated on 22/Oct/15 $${Consider}\:{the}\:{system}\:{of}\:{equations} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\mathrm{2}{yz}+{zx}−\mathrm{5}{xy}=\mathrm{2} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:{yz}−{zx}+\mathrm{2}{xy}=\mathrm{1} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:{yz}−\mathrm{2}{zx}+\mathrm{6}{xy}=\mathrm{3}. \\ $$$${Show}\:{that}\:{xyz}=\pm\mathrm{6}\: \\ $$$${and}\:{find}\:{the}\:{possible}\:{values} \\ $$$${of}\:{x},{y}\:{and}\:{z}. \\ $$ Commented…
Question Number 1898 by 123456 last updated on 22/Oct/15 $$\frac{{df}}{{dt}}=\alpha{f}+\beta{t}+\gamma \\ $$$${f}\left({t}\right)=?? \\ $$ Answered by Yozzy last updated on 22/Oct/15 $$\frac{{df}}{{dt}}=\alpha{f}+\beta{t}+\gamma\:\:\:{where}\:{I}\:{assume}\:{that}\:\alpha,\beta,\gamma\:{are}\:{constants}.\:{This}\:{equation}\:{may}\:{be} \\ $$$${rewritten}\:{as}\:\:\:\:\:\frac{{df}}{{dt}}−\alpha{f}=\beta{t}+\gamma\:\:\left(\ast\right).\:{The}\:{equation}\:{is}\:{a}\:{first}\:{order}\:{linear}\:{non}−{homogeneous} \\…
Question Number 132971 by metamorfose last updated on 17/Feb/21 $$\:\:{Lim}_{{x}\rightarrow\left(\frac{\pi}{\mathrm{2}}\right)^{−\:\:\:} } \frac{\lfloor{sin}\left({x}\right)\rfloor}{{cos}\left({x}\lfloor{x}\rfloor\right)} \\ $$ Answered by mnjuly1970 last updated on 18/Feb/21 $${ans}:\frac{\mathrm{0}}{\mathrm{0}^{+} }=\mathrm{0} \\ $$…
Question Number 67430 by TawaTawa last updated on 27/Aug/19 Commented by MJS last updated on 27/Aug/19 $$\mathrm{coordinate}\:\mathrm{method} \\ $$$$\mathrm{turn}\:\mathrm{the}\:\mathrm{triangle}\:\rightarrow\:{CA}\:\mathrm{is}\:\mathrm{the}\:\mathrm{base} \\ $$$$\mathrm{side}\:\mathrm{length}\:={s} \\ $$$${s}=\mathrm{8}+{x}\:\Rightarrow\:{x}={s}−\mathrm{8} \\ $$$${C}=\begin{pmatrix}{−\frac{{s}}{\mathrm{2}}}\\{\mathrm{0}}\end{pmatrix}\:\:{A}=\begin{pmatrix}{\frac{{s}}{\mathrm{2}}}\\{\mathrm{0}}\end{pmatrix}\:\:{B}=\begin{pmatrix}{\mathrm{0}}\\{\frac{\sqrt{\mathrm{3}}{s}}{\mathrm{2}}}\end{pmatrix}…
Question Number 1895 by Yozzy last updated on 22/Oct/15 $${Let}\:{us}\:{generalise}\:{the}\:{result}\:{of}\:{taking}\:{the}\:{inverse}\:{tangent}\:{of}\:{a}\:{complex}\:{number} \\ $$$${to}\:{the}\:{form}\: \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:{tan}^{−\mathrm{1}} \left({c}+{id}\right)={a}+{ib} \\ $$$${where}\:{a},{b},{c},{d}\in\mathbb{R}\:{and}\:{i}=\sqrt{−\mathrm{1}}.\:{Determine}\:{a}\:{and}\:{b}\:{respectively}\:{in}\:{terms} \\ $$$${of}\:{c}\:{and}\:{d}.\: \\ $$ Commented by Rasheed Soomro…
Question Number 67431 by aliesam last updated on 27/Aug/19 Commented by mathmax by abdo last updated on 27/Aug/19 $${if}\:{a}\:{and}\:{b}\:{from}\:{C}\:{the}\:{question}\:{is}\:{done}\:{by}\:{sir}\:{mjs} \\ $$$${if}\:{a}\:{and}\:{b}\:{from}\:{R}\:\:\:{we}\:{have}\:\:\left(\mid\frac{{a}}{{b}}\mid\right)^{\mathrm{2}} −\left(\frac{\mid{a}\mid}{\mid{b}\mid}\right)^{\mathrm{2}} \: \\ $$$$=\mid\frac{{a}^{\mathrm{2}}…
Question Number 132967 by mohammad17 last updated on 17/Feb/21 $${where}\:{is}\:{function}\:{f}\left({z}\right)={zRez}+\overset{−} {{z}lnz}+\overset{−} {{z}} \\ $$$${derivable}\:,{then}\:{find}\:{the}\:{dervaitive}\:? \\ $$ Commented by mohammad17 last updated on 18/Feb/21 $$????\:\: \\…
Question Number 132961 by danielasebhofoh last updated on 17/Feb/21 Answered by Ar Brandon last updated on 17/Feb/21 $$\mathrm{2n}−\mathrm{3}+\underset{\mathrm{k}=\mathrm{1}} {\overset{\mathrm{n}−\mathrm{3}} {\sum}}\mathrm{k}=\mathrm{2n}−\mathrm{3}+\frac{\left(\mathrm{n}−\mathrm{3}\right)\left(\mathrm{n}−\mathrm{2}\right)}{\mathrm{2}} \\ $$$$\frac{\mathrm{4n}−\mathrm{6}+\mathrm{n}^{\mathrm{2}} −\mathrm{5n}+\mathrm{6}}{\mathrm{2}}=\frac{\mathrm{n}\left(\mathrm{n}−\mathrm{1}\right)}{\mathrm{2}} \\ $$$$\overset{\mathrm{n}}…
Question Number 1890 by Rasheed Soomro last updated on 21/Oct/15 $${Solve}\:{for}\:{x} \\ $$$$\:\:\:\:\:\:{tan}\:{x}\:+{tan}\:\mathrm{2}{x}\:−{tan}\:\mathrm{3}{x}\:=\mathrm{0} \\ $$$${Some}\:{one}\:{had}\:{posted}\:{this}\:{question}\:{and}\:{I}\:{had}\:{answered}\:{it} \\ $$$${but}\:{then}\:{thread}\:{was}\:{deleted}! \\ $$$${I}\:{think}\:{that}\:{the}\:{question}\:{is}\:{not}\:{importanceless}\:,\:{so}\:{I}\:{hav} \\ $$$${reposted}\:{it}. \\ $$ Commented by…
Question Number 67422 by mr W last updated on 27/Aug/19 Commented by Prithwish sen last updated on 27/Aug/19 $$\bigtriangleup\mathrm{AMN}\:\mathrm{is}\:\mathrm{an}\:\mathrm{isoceles}\:\mathrm{triangle}\:\mathrm{with}\:\mathrm{AM}=\mathrm{AN} \\ $$$$\mathrm{AM}+\mathrm{BM}=\:\mathrm{AN}+\mathrm{D}^{'} \mathrm{N}=\mathrm{16} \\ $$$$\mathrm{Area}\:\mathrm{ABMND}^{'} =\:\mathrm{Area}\:\mathrm{of}\:\mathrm{ABCD}\:−\mathrm{Area}\:\mathrm{of}\:\bigtriangleup\mathrm{AMN}.…