Question

Calcule o 100° termo da P.A (5;9;13....)

Answer 1

a₁ = 5
a₂ = 9
a₃ = 13
n = 100
r = 9 - 5 = 4

a₁₀₀ = a₁ + (n - 1) . r
a₁₀₀ = 5 + (100 - 1) . 4
a₁₀₀ = 5 + 99 . 4
a₁₀₀ = 5 + 396
a₁₀₀ = 401

Espero ter ajudado. Valeu!

Answer 2

Vamos encontrar a razão:

$r=a_2-a_1\\\\ r=9-5\\\\ \boxed{r=4}$

$a_n=a_1+(n-1)*r\\\\ a_1_0_0=a_1+(100-1)*r\\\\ a_1_0_0=a_1+99r\\\\ a_1_0_0=5+99*4\\\\ a_1_0_0=5+396\\\\ \boxed{a_1_0_0=401}$