Question Number 55658 by otchereabdullai@gmail.com last updated on 01/Mar/19
$$\mathrm{find}\:\mathrm{the}\:\mathrm{difference}\:\mathrm{of}\:\mathrm{the}\:\mathrm{roots}\:\mathrm{of}\:\mathrm{the}\: \\ $$$$\mathrm{following}\:\mathrm{quadratic}\:\mathrm{equation} \\ $$$$\left(\mathrm{3}+\mathrm{2}\sqrt{\mathrm{2}\:}\right)\mathrm{x}^{\mathrm{2}} \:+\left(\mathrm{1}+\sqrt{\mathrm{2}}\right)\mathrm{x}\:=\mathrm{2} \\ $$
Answered by tanmay.chaudhury50@gmail.com last updated on 01/Mar/19
$$\alpha+\beta=−\frac{\left(\mathrm{1}+\sqrt{\mathrm{2}}\:\right)}{\mathrm{3}+\mathrm{2}\sqrt{\mathrm{2}}\:}\:\:\:\alpha\beta=\frac{−\mathrm{2}}{\mathrm{3}+\mathrm{2}\sqrt{\mathrm{2}}\:} \\ $$$$\left(\alpha−\beta\right)^{\mathrm{2}} =\left(\alpha+\beta\right)^{\mathrm{2}} −\mathrm{4}\alpha\beta \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\frac{\mathrm{1}+\mathrm{2}\sqrt{\mathrm{2}}\:+\mathrm{2}}{\left(\mathrm{3}+\mathrm{2}\sqrt{\mathrm{2}}\:\right)^{\mathrm{2}} }−\mathrm{4}\left(\frac{−\mathrm{2}}{\mathrm{3}+\mathrm{2}\sqrt{\mathrm{2}}\:}\right) \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\frac{\mathrm{3}+\mathrm{2}\sqrt{\mathrm{2}}}{\left(\mathrm{3}+\mathrm{2}\sqrt{\mathrm{2}}\:\right)^{\mathrm{2}} }+\frac{\mathrm{8}}{\mathrm{3}+\mathrm{2}\sqrt{\mathrm{2}}\:} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\frac{\mathrm{1}}{\mathrm{3}+\mathrm{2}\sqrt{\mathrm{2}}\:}+\frac{\mathrm{8}}{\mathrm{3}+\mathrm{2}\sqrt{\mathrm{2}}} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\frac{\mathrm{9}}{\mathrm{3}+\mathrm{2}\sqrt{\mathrm{2}}} \\ $$$$\left(\alpha−\beta\right)=\sqrt{\frac{\mathrm{9}}{\mathrm{3}+\mathrm{2}\sqrt{\mathrm{2}}}} \\ $$$$\:\:\:\:\:\:\:\:\:\:\:\:\:\:=\frac{\mathrm{3}}{\:\sqrt{\mathrm{2}}\:+\mathrm{1}} \\ $$
Commented by otchereabdullai@gmail.com last updated on 01/Mar/19
$$\mathrm{Thank}\:\mathrm{you}\:\mathrm{Prof} \\ $$
Commented by mr W last updated on 01/Mar/19
$${please}\:{check}\:{sir},\:{should}\:{it}\:{not}\:{be}: \\ $$$$\frac{\mathrm{3}}{\:\sqrt{\mathrm{2}}+\mathrm{1}}=\mathrm{3}\left(\sqrt{\mathrm{2}}−\mathrm{1}\right)\:? \\ $$
Commented by tanmay.chaudhury50@gmail.com last updated on 01/Mar/19
$${yes}\:{sir}..{in}\:{hurry}… \\ $$
Commented by malwaan last updated on 02/Mar/19
$$\sqrt{\frac{\mathrm{9}\left(\mathrm{3}−\mathrm{2}\sqrt{\mathrm{2}}\right)}{\mathrm{9}−\mathrm{8}}}=\mathrm{3}\sqrt{\mathrm{3}−\mathrm{2}\sqrt{\mathrm{2}}} \\ $$
Commented by mr W last updated on 02/Mar/19
$${and}\:\mathrm{3}\sqrt{\mathrm{3}−\mathrm{2}\sqrt{\mathrm{2}}}=\mathrm{3}\sqrt{\left(\sqrt{\mathrm{2}}−\mathrm{1}\right)^{\mathrm{2}} }=\mathrm{3}\left(\sqrt{\mathrm{2}}−\mathrm{1}\right) \\ $$
Commented by otchereabdullai@gmail.com last updated on 02/Mar/19
$$\:\:\mathrm{thanks}\:\mathrm{Sir}\:\mathrm{malwaan}\:\mathrm{and}\:\mathrm{Prof}\:\mathrm{W}\:\mathrm{for}\: \\ $$$$\mathrm{the}\:\mathrm{correction} \\ $$