Question

determine o 32° termo da p.a (16,12,18,24,30...)

Answer 1

Primeiro vamos encontrar a Razão : 

$\mathtt{R = A_2 - A_1} \\ \mathtt{R = 12 - 16} \\ \mathtt{R = -4}$

Agora aplicaremos a formula de P.A

$\mathtt{A_{n} = A_1 + (n-1)~.~R} \\ \mathtt{A_{32} = 16 + (32-1)~.~(-4)} \\ \mathtt{A_{32} = 16 + 31~.~(-4)} \\ \mathtt{A_{32} = 16 -124} \\ \mathtt{A_{32} = -108 } \\ \\ \\ \boxed{\boxed{\mathtt{Resposta: -108}}}$

Answer 2

a1=16
r=6

An= a1 + (n-1)r
A32=16+31*6
A32=16+186
A32= 20 2