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Author: Tinku Tara

determinant-lim-x-0-1-x-sin-x-cos-x-sin-2-x-

Question Number 195148 by horsebrand11 last updated on 25/Jul/23 $$\:\:\begin{array}{|c|}{\underset{{x}\rightarrow\mathrm{0}} {\mathrm{lim}}\:\frac{\mathrm{1}+\mathrm{x}\:\mathrm{sin}\:\mathrm{x}−\mathrm{cos}\:\mathrm{x}}{\mathrm{sin}\:^{\mathrm{2}} \mathrm{x}}=?}\\\hline\end{array} \\ $$ Answered by Erico last updated on 25/Jul/23 $$\frac{\mathrm{1}+\mathrm{xsinx}−\mathrm{cosx}}{\mathrm{sin}^{\mathrm{2}} \mathrm{x}}=\frac{\mathrm{1}−\mathrm{cosx}}{\mathrm{sin}^{\mathrm{2}} \mathrm{x}}+\frac{\mathrm{x}}{\mathrm{sinx}} \\…

a-b-c-gt-0-amp-1-a-1-b-1-c-3-prove-that-a-b-2-c-2-b-a-2-c-2-c-a-2-b-2-3-2-a-b-c-ab-bc-ac-2-

Question Number 195118 by York12 last updated on 25/Jul/23 $${a},{b},{c}>\mathrm{0}\:\&\:\frac{\mathrm{1}}{{a}}+\frac{\mathrm{1}}{{b}}+\frac{\mathrm{1}}{{c}}=\mathrm{3} \\ $$$${prove}\:{that} \\ $$$$\frac{{a}}{{b}^{\mathrm{2}} +{c}^{\mathrm{2}} }+\frac{{b}}{{a}^{\mathrm{2}} +{c}^{\mathrm{2}} }+\frac{{c}}{{a}^{\mathrm{2}} +{b}^{\mathrm{2}} }\geqslant\frac{\mathrm{3}}{\mathrm{2}}\left(\frac{{a}+{b}+{c}}{{ab}+{bc}+{ac}}\right)^{\mathrm{2}} \\ $$ Commented by York12…

Question-195175

Question Number 195175 by valdirmd last updated on 25/Jul/23 Answered by Rasheed.Sindhi last updated on 26/Jul/23 $${x}^{\mathrm{4}} +{x}^{\mathrm{2}} =\mathrm{11}/\mathrm{5}\:,\:\left(\frac{{x}+\mathrm{1}}{{x}−\mathrm{1}}\right)^{\mathrm{1}/\mathrm{3}} +\left(\frac{{x}−\mathrm{1}}{{x}+\mathrm{1}}\right)^{\mathrm{1}/\mathrm{3}} =? \\ $$$$\blacktriangleright{Let}\:{y}=\left(\frac{{x}+\mathrm{1}}{{x}−\mathrm{1}}\right)^{\mathrm{1}/\mathrm{3}} +\left(\frac{{x}−\mathrm{1}}{{x}+\mathrm{1}}\right)^{\mathrm{1}/\mathrm{3}} \\…

f-x-arctan-4sinx-3-5cosx-then-f-pi-3-

Question Number 195137 by mathlove last updated on 25/Jul/23 $${f}\left({x}\right)={arctan}\left(\frac{\mathrm{4}{sinx}}{\mathrm{3}+\mathrm{5}{cosx}}\right)\:\:\:{then}\:{f}^{'} \left(\frac{\pi}{\mathrm{3}}\right)=? \\ $$ Answered by Tokugami last updated on 02/Sep/23 $${f}'\left({x}\right)=\frac{\mathrm{1}}{\mathrm{1}+\left(\frac{\mathrm{4sin}\:{x}}{\mathrm{3}+\mathrm{5cos}\:{x}}\right)^{\mathrm{2}} }\:\frac{{d}}{{dx}}\left(\frac{\mathrm{4sin}\:{x}}{\mathrm{3}+\mathrm{5cos}\:{x}}\right) \\ $$$$=\frac{\mathrm{1}}{\mathrm{1}+\frac{\mathrm{16sin}^{\mathrm{2}} {x}}{\left(\mathrm{3}+\mathrm{5cos}\:{x}\right)^{\mathrm{2}}…

f-x-arctan-sinx-and-cosa-2-3-faind-f-a-

Question Number 195136 by mathlove last updated on 25/Jul/23 $${f}\left({x}\right)={arctan}\left({sinx}\right) \\ $$$${and}\:\:{cosa}=\frac{\mathrm{2}}{\mathrm{3}}\:\:\:\:\:\:\:\:{faind}\:\:\:{f}^{'} \left({a}\right)=? \\ $$ Answered by som(math1967) last updated on 25/Jul/23 $$\:\boldsymbol{{f}}\:'\left({x}\right)=\frac{\mathrm{1}}{\mathrm{1}+\boldsymbol{{sin}}^{\mathrm{2}} \boldsymbol{{x}}}×\boldsymbol{{cosx}} \\…

f-x-x-7-2x-1-x-2-x-2-7x-4-x-lt-1-f-1-

Question Number 195170 by mathlove last updated on 25/Jul/23 $${f}\left({x}\right)=\begin{cases}{{x}^{\mathrm{7}} +\mathrm{2}{x}+\mathrm{1}\:\:\:\:\:\:\:;{x}\geqslant\mathrm{2}}\\{{x}^{\mathrm{2}} +\mathrm{7}{x}+\mathrm{4}\:\:\:\:\:\:\:\:;{x}<\mathrm{1}}\end{cases} \\ $$$${f}^{'} \left(\mathrm{1}\right)=? \\ $$ Answered by MM42 last updated on 25/Jul/23 $${f}\left(\mathrm{1}\right)\:,\:{not}\:{available}\:{so}…