Réponse :
Explications étape par étape :
■ a = -1 = cos(-π) + i sin(-π) = e^( - i π )
■ b = 2i = 2 [ (cos(π/2) + i sin(π/2) ] = 2 e^( i π/2 )
■ c = 1/2 - i √3 /2 = cos(-π/3) + i sin(-π/3) = e^( - i π/3 )
■ √3 + 3i = (2√3) [ cos(π/3) + i sin(π/3) ] = (2√3) e^( i π/3 )
■ e = (1 - i)³ = 1 - 3i - 3 + i = -2 - 2i = 2√2 [ cos(-3π/4) + i sin(-3π/4) ]
= 2√2 e^( - 3π/4 )
■ (1 + i)^2022 = ?
( 1 + i )² = 2 i
( 2 i )³ = - 8 i
(1 + i)^2022 = (2i)^1011 = ( - 8 i )^337 = 8^337 * ( - i )^337
or ( - i )^² = -1 ; ( - i )³ = i ; ( - i )^4 = +1 ; ...
donc ( - i )^337 = - i ( car 337 = 84*4 + 1 )
d' où ( 1 + i )^2022 = 8^337 * ( - i ) = 2^1011 * ( - i ) .
je Te laisse trouver un chemin plus court pour cette réponse ! ☺
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Réponse :
Explications étape par étape :
■ a = -1 = cos(-π) + i sin(-π) = e^( - i π )
■ b = 2i = 2 [ (cos(π/2) + i sin(π/2) ] = 2 e^( i π/2 )
■ c = 1/2 - i √3 /2 = cos(-π/3) + i sin(-π/3) = e^( - i π/3 )
■ √3 + 3i = (2√3) [ cos(π/3) + i sin(π/3) ] = (2√3) e^( i π/3 )
■ e = (1 - i)³ = 1 - 3i - 3 + i = -2 - 2i = 2√2 [ cos(-3π/4) + i sin(-3π/4) ]
= 2√2 e^( - 3π/4 )
■ (1 + i)^2022 = ?
( 1 + i )² = 2 i
( 2 i )³ = - 8 i
(1 + i)^2022 = (2i)^1011 = ( - 8 i )^337 = 8^337 * ( - i )^337
or ( - i )^² = -1 ; ( - i )³ = i ; ( - i )^4 = +1 ; ...
donc ( - i )^337 = - i ( car 337 = 84*4 + 1 )
d' où ( 1 + i )^2022 = 8^337 * ( - i ) = 2^1011 * ( - i ) .
je Te laisse trouver un chemin plus court pour cette réponse ! ☺