Răspuns :
∛26+15√3+∛26-15√3=
pt a elimina radicalul ridicam toata funcia la puterea radicalului
∛(2+√3)³+∛(2-√3)³=
2+√3+2-√3=4
succes
pt a elimina radicalul ridicam toata funcia la puterea radicalului
∛(2+√3)³+∛(2-√3)³=
2+√3+2-√3=4
succes
Avem formulele: (a+b)³=a³+2a²b+3ab²+b³,si (a-b)³=a³-3a²b+3ab²-b³, aplicand formulele invers , resrangem expresiile de sub radical la:
[tex] \sqrt[3]{(2+ \sqrt{3})^3 }+ \sqrt[3]{(2- \sqrt{3})^3 }=2+ \sqrt{3}+2- \sqrt{3}=4 [/tex]
Verificare [tex](2+ \sqrt{3})^3=2^3+3*2^2* \sqrt{3}+3*2* \sqrt{3}^2+ \sqrt{3}^3=26+15 \sqrt{3} [/tex]
[tex] \sqrt[3]{(2+ \sqrt{3})^3 }+ \sqrt[3]{(2- \sqrt{3})^3 }=2+ \sqrt{3}+2- \sqrt{3}=4 [/tex]
Verificare [tex](2+ \sqrt{3})^3=2^3+3*2^2* \sqrt{3}+3*2* \sqrt{3}^2+ \sqrt{3}^3=26+15 \sqrt{3} [/tex]