Question

calcule:a;12 termo da p.a.(-8,-3,2,...) b;30 termo da p.a.(5,8,11,...)c;121 termo da p.a.(32,26,20,...)

Answer 1

Oi Maria

a)

PA(-8,-3,2,...) 

r = -3 + 8 = 5
a12 = a1 + 11r
a12 = -8 + 55 = 47 

b)

PA(5,8,11,...)

r = 8 - 5 = 3
a30 = a1 + 29r
a30 = 5 + 87 = 92 

c) PA(32,26,20,...)

r = 26 - 32 = -6
a121 = a1 + 120r
a121 = 32 - 720 = -688