Question

Determinar a pg cuja razao e 3/2 e a soma dos 5 primeiros termos e 422?

Answer 1

q=3/2

Sn=a1*(1-q^n)/(1-q)

S5=a1*(1-(3/2)^5)/(1-3/2)=422

a1*(1-(3/2)^5)/(-1/2))=422

a1*(1-(3/2)^5)=-2*422

a1*(1-243/32)=-2*422

a1*(32/32-243/32)=-2*422

a1*(-211)=-2*422 *32

a1=2*422 *32/211 =128 

a2=128*3/2 =192

a3=192*3/2=288

a4=288 *3/2 =432

a5=432*3/2 = 648