Question

3) Dada a PA (16, X, 26, ...). Calcule o vigésimo quinto termo da PA.​

Answer 1

Resposta:

$16 = a_1\\\\26 = a_1 + 2\cdot r = 16 + 2\cdot r \rightarrow 26 - 16 = 10 = 2\cdot r \rightarrow r = 5\\\\a_{25} = a_1 + (n-1)\cdot r = 16 + (25-1)\cdot 5 = 16 + 24\cdot 5 = 16 + 120 = 136$

Answer 2

Resposta:

Explicação passo a passo:

P.A.(16,X,26,...)

r = a₂ - a₁

r = x - 16

r = a₃ - a₂

r = 26 - x

x - 16 = 26 - x

x + x = 26 + 16

2x = 42

x = 42/2

x = 21

P.A.(16,21,26,...)

r = a₂ - a₁

r = 21 - 16

r = 5

aₙ = a₁ + (n - 1) . r

a₂₅ = 16 + (25 - 1) . 5

a₂₅ = 16 + 24 . 5

a₂₅ = 16 + 120

a₂₅ = 136