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Question Number 46110 by Tawa1 last updated on 21/Oct/18

Commented by math khazana by abdo last updated on 22/Oct/18

Δ=1−4=−3=(i(√3))^2 ⇒α=((1+i(√3))/2) and β=((1−i(√3))/2)  ⇒α=e^(i(π/3))  and β =e^(−i(π/3))  ⇒α^(101) =e^(i((101)/3)π)   = e^(i(((99 +2)/3))π) =e^(33iπ)  e^(i((2π)/3))  =−j  β^(107) = e^(−i((107)/3)π)  =e^(−i((101)/3)π)  e^(−i((6π)/3)) = e^(−i33π) e^(−i((2π)/3))   =−j^−  ⇒α^(101)  +β^(107)  =−j−j^− =−(j+j^− )  =−(1+j+j^− ) +1=0+1 =1

Δ=14=3=(i3)2α=1+i32andβ=1i32α=eiπ3andβ=eiπ3α101=ei1013π=ei(99+23)π=e33iπei2π3=jβ107=ei1073π=ei1013πei6π3=ei33πei2π3=jα101+β107=jj=(j+j)=(1+j+j)+1=0+1=1

Commented by Tawa1 last updated on 22/Oct/18

God bless you sir

Godblessyousir

Answered by ajfour last updated on 21/Oct/18

x^3 +1 = (x+1)(x^2 −x+1)  roots of     x^3 +1=0  are  −1, −ω^2 , −ω  So    (−ω)^(101) +(−ω^2 )^(107)  = −ω^2 −ω        = 1 .

x3+1=(x+1)(x2x+1)rootsofx3+1=0are1,ω2,ωSo(ω)101+(ω2)107=ω2ω=1.

Commented by Tawa1 last updated on 21/Oct/18

God bless you sir. but i don′t really understand sir.  from the  (− ω)  and the substitution to get  1

Godblessyousir.butidontreallyunderstandsir.fromthe(ω)andthesubstitutiontoget1

Commented by $@ty@m last updated on 21/Oct/18

x^3 +1=0  ⇒(x+1)(x^2 −x+1)=0  ⇒x+1=0 or x^2 −x+1=0  ⇒x=−1 or x=−ω, −ω^2   i.e. roots of x^2 −x+1 are −ω, −ω^2   ∴ α=−ω, β=−ω^2

x3+1=0(x+1)(x2x+1)=0x+1=0orx2x+1=0x=1orx=ω,ω2i.e.rootsofx2x+1areω,ω2α=ω,β=ω2

Commented by Tawa1 last updated on 21/Oct/18

God bless you sir.

Godblessyousir.

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