Menu Close

a-b-c-d-e-f-Q-1-2-2-1-3-2-a-2-b-2-c-2-d-2-e-2-f-find-a-b-c-d-e-f-




Question Number 214443 by hardmath last updated on 08/Dec/24
a,b,c,d,e,f ∈ Q  (1/( (√2) − (2)^(1/3) )) = 2^a  + 2^b  + 2^c  + 2^d  + 2^e  + 2^f   find:   a,b,c,d,e,f = ?
$$\mathrm{a},\mathrm{b},\mathrm{c},\mathrm{d},\mathrm{e},\mathrm{f}\:\in\:\mathrm{Q} \\ $$$$\frac{\mathrm{1}}{\:\sqrt{\mathrm{2}}\:−\:\sqrt[{\mathrm{3}}]{\mathrm{2}}}\:=\:\mathrm{2}^{\boldsymbol{\mathrm{a}}} \:+\:\mathrm{2}^{\boldsymbol{\mathrm{b}}} \:+\:\mathrm{2}^{\boldsymbol{\mathrm{c}}} \:+\:\mathrm{2}^{\boldsymbol{\mathrm{d}}} \:+\:\mathrm{2}^{\boldsymbol{\mathrm{e}}} \:+\:\mathrm{2}^{\boldsymbol{\mathrm{f}}} \\ $$$$\mathrm{find}:\:\:\:\mathrm{a},\mathrm{b},\mathrm{c},\mathrm{d},\mathrm{e},\mathrm{f}\:=\:? \\ $$
Answered by ajfour last updated on 08/Dec/24
(1/(a^3 −a^2 ))=((a^6 +a^4 +a^5 )/(a^9 −a^6 ))=((2+2^(2/3) +2^(5/6) )/(2(√2)−2))  =(((2+2^(2/3) +2^(5/6) )(2(√2)+2))/4)  =(1+(1/2^(1/3) )+(1/2^(1/6) ))(2^(1/2) +1)  =1+(1/2^(1/3) )+(1/2^(1/6) )+2^(1/2) +2^(1/6) +2^(1/3)   will this do?
$$\frac{\mathrm{1}}{{a}^{\mathrm{3}} −{a}^{\mathrm{2}} }=\frac{{a}^{\mathrm{6}} +{a}^{\mathrm{4}} +{a}^{\mathrm{5}} }{{a}^{\mathrm{9}} −{a}^{\mathrm{6}} }=\frac{\mathrm{2}+\mathrm{2}^{\mathrm{2}/\mathrm{3}} +\mathrm{2}^{\mathrm{5}/\mathrm{6}} }{\mathrm{2}\sqrt{\mathrm{2}}−\mathrm{2}} \\ $$$$=\frac{\left(\mathrm{2}+\mathrm{2}^{\mathrm{2}/\mathrm{3}} +\mathrm{2}^{\mathrm{5}/\mathrm{6}} \right)\left(\mathrm{2}\sqrt{\mathrm{2}}+\mathrm{2}\right)}{\mathrm{4}} \\ $$$$=\left(\mathrm{1}+\frac{\mathrm{1}}{\mathrm{2}^{\mathrm{1}/\mathrm{3}} }+\frac{\mathrm{1}}{\mathrm{2}^{\mathrm{1}/\mathrm{6}} }\right)\left(\mathrm{2}^{\mathrm{1}/\mathrm{2}} +\mathrm{1}\right) \\ $$$$=\mathrm{1}+\frac{\mathrm{1}}{\mathrm{2}^{\mathrm{1}/\mathrm{3}} }+\frac{\mathrm{1}}{\mathrm{2}^{\mathrm{1}/\mathrm{6}} }+\mathrm{2}^{\mathrm{1}/\mathrm{2}} +\mathrm{2}^{\mathrm{1}/\mathrm{6}} +\mathrm{2}^{\mathrm{1}/\mathrm{3}} \\ $$$${will}\:{this}\:{do}? \\ $$

Leave a Reply

Your email address will not be published. Required fields are marked *