Question

calcule p decimo terceiro termo da pa(3,7...)

Answer 1

An = A₁ + (n - 1) x r

r = A₂ - A₁ = 7 - 3 = 4
A₁ = 3
n = 13

A₁₃ = 3 + (13 - 1) x 4
A₁₃ = 3 + 12 x 4

A₁₃ = 51

P.A.: {3, 7, 11, 15, 19, 23, 27, 31, 35, 39, 43, 47, 51}

Answer 2

Encontar a razão da PA

r = a2 - a1
r = 7 - 3
r = 4

===

an =   a1 + ( n -1 ) . r
a13 =  3 + ( 13 -1 ) . 4
a13 =  3 + 12 . 4
a13 =  3 + 48
a13 =  51