Question Number 80448 by mind is power last updated on 03/Feb/20
$${Hello}\:{All}\:{of}\:{You}\:{verry}\:{Nice}\:{Day},\:{God}\:{bless}\:{You}\:{love}\:{peace}\:{and}\: \\ $$$${happiness}\: \\ $$$${Solve}\:{for}\:\left({x},{y}\right)\in\mathbb{R}^{\mathrm{2}} \: \\ $$$$\begin{cases}{{x}^{\mathrm{2}} +{y}^{\mathrm{2}} =\mathrm{2}{x}+\mathrm{3}{y}+\mathrm{1}}\\{{x}^{\mathrm{4}} +{y}^{\mathrm{4}} =\mathrm{4}{x}^{\mathrm{2}} +\mathrm{9}{y}^{\mathrm{2}} +\mathrm{12}{xy}+\mathrm{2}{x}^{\mathrm{2}} {y}^{\mathrm{2}} +\mathrm{18}}\end{cases} \\ $$$$ \\ $$
Commented by mr W last updated on 03/Feb/20
$${thank}\:{you}\:{sir}!\:{the}\:{same}\:{to}\:{you}! \\ $$
Commented by john santu last updated on 03/Feb/20
$${x}^{\mathrm{4}} +{y}^{\mathrm{4}} =\left({x}^{\mathrm{2}} +{y}^{\mathrm{2}} \right)^{\mathrm{2}} −\mathrm{2}{x}^{\mathrm{2}} {y}^{\mathrm{2}} \\ $$$$\left(\mathrm{2}{x}+\mathrm{3}{y}+\mathrm{1}\right)^{\mathrm{2}} −\mathrm{2}{x}^{\mathrm{2}} {y}^{\mathrm{2}} =\mathrm{4}{x}^{\mathrm{2}} +\mathrm{9}{y}^{\mathrm{2}} +\mathrm{12}{xy}+\mathrm{2}{x}^{\mathrm{2}} {y}^{\mathrm{2}} +\mathrm{18} \\ $$$$\mathrm{4}{x}^{\mathrm{2}} +\mathrm{9}{y}^{\mathrm{2}} +\mathrm{1}+\mathrm{2}\left(\mathrm{6}{xy}+\mathrm{2}{x}+\mathrm{3}{y}\right)−\mathrm{2}{x}^{\mathrm{2}} {y}^{\mathrm{2}} = \\ $$$$\mathrm{4}{x}^{\mathrm{2}} +\mathrm{9}{y}^{\mathrm{2}} +\mathrm{12}{xy}+\mathrm{2}{x}^{\mathrm{2}} {y}^{\mathrm{2}} +\mathrm{18} \\ $$$$\mathrm{1}+\mathrm{4}{x}+\mathrm{6}{y}−\mathrm{2}{x}^{\mathrm{2}} {y}^{\mathrm{2}} =\mathrm{2}{x}^{\mathrm{2}} {y}^{\mathrm{2}} +\mathrm{18} \\ $$$$\mathrm{4}{x}^{\mathrm{2}} {y}^{\mathrm{2}} −\mathrm{4}{x}−\mathrm{6}{y}+\mathrm{17}=\mathrm{0} \\ $$$$\mathrm{4}{x}^{\mathrm{2}} {y}^{\mathrm{2}} −\mathrm{2}\left(\mathrm{2}{x}+\mathrm{3}{y}\right)+\mathrm{17}=\mathrm{0} \\ $$$$\mathrm{4}{x}^{\mathrm{2}} {y}^{\mathrm{2}} −\mathrm{2}\left({x}^{\mathrm{2}} +{y}^{\mathrm{2}} −\mathrm{1}\right)+\mathrm{17}=\mathrm{0} \\ $$$$\mathrm{2}\left({x}^{\mathrm{2}} +{y}^{\mathrm{2}} \right)−\mathrm{4}{x}^{\mathrm{2}} {y}^{\mathrm{2}} −\mathrm{19}=\mathrm{0} \\ $$$${let}\:{x}^{\mathrm{2}} \:=\:{t}\:,\:{y}^{\mathrm{2}} ={p}\: \\ $$$$\mathrm{2}\left({t}+{p}\right)−\mathrm{4}{tp}−\mathrm{19}=\mathrm{0} \\ $$$${next}… \\ $$
Commented by jagoll last updated on 03/Feb/20
$${to}\:{be}\:{continue} \\ $$
Answered by MJS last updated on 03/Feb/20
$$\mathrm{let}\:{x}={u}−{v}\wedge{y}={u}+{v} \\ $$$$\begin{cases}{\mathrm{2}{u}^{\mathrm{2}} +\mathrm{2}{v}^{\mathrm{2}} =\mathrm{5}{u}+{v}+\mathrm{1}}\\{\mathrm{2}{u}^{\mathrm{4}} +\mathrm{12}{u}^{\mathrm{2}} {v}^{\mathrm{2}} +\mathrm{2}{v}^{\mathrm{4}} =\mathrm{2}{u}^{\mathrm{4}} −\mathrm{4}{u}^{\mathrm{2}} {v}^{\mathrm{2}} +\mathrm{2}{v}^{\mathrm{4}} +\mathrm{25}{u}^{\mathrm{2}} +\mathrm{10}{uv}+{v}^{\mathrm{2}} +\mathrm{18}}\end{cases} \\ $$$$\begin{cases}{\mathrm{2}{u}^{\mathrm{2}} +\mathrm{2}{v}^{\mathrm{2}} −\mathrm{5}{u}−{v}−\mathrm{1}=\mathrm{0}}\\{\mathrm{16}{u}^{\mathrm{2}} {v}^{\mathrm{2}} −\mathrm{25}{u}^{\mathrm{2}} −\mathrm{10}{uv}−{v}^{\mathrm{2}} −\mathrm{18}=\mathrm{0}}\end{cases} \\ $$$$\begin{cases}{{v}^{\mathrm{2}} −\frac{{v}}{\mathrm{2}}+\frac{\mathrm{2}{u}^{\mathrm{2}} −\mathrm{5}{u}−\mathrm{1}}{\mathrm{2}}=\mathrm{0}}\\{{v}^{\mathrm{2}} −\frac{\mathrm{10}{u}}{\mathrm{16}{u}^{\mathrm{2}} −\mathrm{1}}{v}−\frac{\mathrm{25}{u}^{\mathrm{2}} +\mathrm{18}}{\mathrm{16}{u}^{\mathrm{2}} −\mathrm{1}}=\mathrm{0}}\end{cases} \\ $$$$\mathrm{subtracting}\:\left(\mathrm{1}\right)\:−\:\left(\mathrm{2}\right)\:\mathrm{and}\:\mathrm{solving}\:\mathrm{for}\:{v}\:\mathrm{leads}\:\mathrm{to} \\ $$$${v}=\frac{\mathrm{32}{u}^{\mathrm{4}} −\mathrm{80}{u}^{\mathrm{3}} +\mathrm{32}{u}^{\mathrm{2}} +\mathrm{5}{u}+\mathrm{37}}{\mathrm{16}{u}^{\mathrm{2}} −\mathrm{20}{u}−\mathrm{1}} \\ $$$$\mathrm{inserting}\:\mathrm{in}\:\left(\mathrm{1}\right)\:\mathrm{or}\:\left(\mathrm{2}\right)\:\mathrm{leads}\:\mathrm{to}\:\mathrm{a}\:\mathrm{polynome}\:\mathrm{of} \\ $$$$\mathrm{8}^{\mathrm{th}} \:\mathrm{degree}\:\mathrm{for}\:{u}\:\mathrm{I}\:\mathrm{can}\:\mathrm{only}\:\mathrm{solve}\:\mathrm{approximately} \\ $$$$\Rightarrow \\ $$$$\left(\mathrm{all}\:\mathrm{rounded}\:\mathrm{to}\:\mathrm{6}\:\mathrm{significant}\:\mathrm{digits}\right) \\ $$$${x}_{\mathrm{1}} =−.\mathrm{184612}\:\:{y}_{\mathrm{1}} =\mathrm{3}.\mathrm{18722} \\ $$$${x}_{\mathrm{2}} =.\mathrm{323632}\:\:{y}_{\mathrm{2}} =\mathrm{3}.\mathrm{44744} \\ $$$${x}_{\mathrm{3},\:\mathrm{4}} =−\mathrm{1}.\mathrm{37362}\pm.\mathrm{450762i}\:\:{y}_{\mathrm{3},\:\mathrm{4}} =.\mathrm{705266}\mp\mathrm{1}.\mathrm{34628i} \\ $$$${x}_{\mathrm{5},\:\mathrm{6}} =.\mathrm{618559}\pm\mathrm{1}.\mathrm{80074}\:\:{y}_{\mathrm{5},\:\mathrm{6}} =−\mathrm{1}.\mathrm{22229}\mp.\mathrm{252316i} \\ $$$${x}_{\mathrm{7},\:\mathrm{8}} =\mathrm{2}.\mathrm{68555}\pm.\mathrm{324293i}\:\:{y}_{\mathrm{7},\:\mathrm{8}} =.\mathrm{199692}\pm.\mathrm{420370i} \\ $$$$\mathrm{these}\:\mathrm{solutions}\:\mathrm{give}\:\mathrm{the}\:\mathrm{folliwing}\:\mathrm{polynomes}: \\ $$$${x}^{\mathrm{8}} −\mathrm{4}{x}^{\mathrm{7}} +\mathrm{2}{x}^{\mathrm{6}} +\mathrm{6}{x}^{\mathrm{5}} −\mathrm{16}{x}^{\mathrm{4}} +\mathrm{15}{x}^{\mathrm{3}} +\frac{\mathrm{109}}{\mathrm{2}}{x}^{\mathrm{2}} −\frac{\mathrm{17}}{\mathrm{2}}{x}−\frac{\mathrm{53}}{\mathrm{16}}=\mathrm{0} \\ $$$${y}^{\mathrm{8}} −\mathrm{6}{y}^{\mathrm{7}} +\mathrm{7}{y}^{\mathrm{6}} +\mathrm{9}{y}^{\mathrm{5}} −\frac{\mathrm{37}}{\mathrm{2}}{y}^{\mathrm{4}} +\frac{\mathrm{45}}{\mathrm{2}}{y}^{\mathrm{3}} +\frac{\mathrm{123}}{\mathrm{4}}{y}^{\mathrm{2}} −\frac{\mathrm{51}}{\mathrm{4}}{y}+\frac{\mathrm{137}}{\mathrm{16}}=\mathrm{0} \\ $$
Commented by mind is power last updated on 04/Feb/20
$${thank}\:{You}\:{Sir}\:{nice}\:{Worck} \\ $$$$ \\ $$