Question

Mă poate ajuta cineva vă rog frumos? E1 b,c,d ; E2 b ; E3 b,c,d

Answer 1

Răspuns:

Explicație pas cu pas:

1)b) 2 ; 1 ; 1/2 => q = b₂/b₁ = 1/2

Tₙ = 2·(1/2)ⁿ⁻¹

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c) -1 ; 1/3 ; -1/9 => q = b₂/b₁ = 1/3/(-1) = -1/3

Tₙ = (-1)·(-1/3)ⁿ⁻¹

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d) √2 ; 1 ; √2/2 ; 1/2 => q = b₂/b₁ = 1/√2 = √2/2

Tₙ = √2 ·(√2/2)ⁿ⁻¹

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2) b) b₉ = 768 ; b₁₁ = 3072 => q² = b₁₁/b₉ = 3072/768 => q² = 4

q₁,₂ = ±2

b₁ = b₉/q⁸ = 768/(±2)⁸ = 768/256 => b₁ = 3

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3) b) b₁ = 2,5 ; q = 1,5 ; n = 5

S₅ = b₁(1+q+q²+q³+q⁴) = 2,5 ·(1+1,5+2,25+3,375+5,0625) =

= 2,5·13,1875 = 32,96875

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