[tex] \displaystyle\\
b_1=60\\\\
q=\frac{1}{2}\\\\
\text{Calcule:}\\\\
b_2 = b_1 \times q = 60\times \frac{1}{2} = \frac{60}{2}=30\\\\
b_3 = b_2 \times q = 30\times \frac{1}{2} = \frac{30}{2}=15\\\\
b_4 = b_3 \times q = 15\times \frac{1}{2} = \frac{15}{2}=7,\!5\\\\
\text{Primii 4 termeni ai progresiei geometrice sunt: }\\
\bf\\
b_1=60\\
b_2=30\\
b_3=15\\
b_4=7,\!5 [/tex]
Forma generala a progresiei geometrice este:
a ; a·q ; a·q² ; . . . . ; a· qⁿ⁻¹
unde a este primul termen iar q ratia progresiei.
In cazul exemplului dat , avem:
60 ;
b₂= 60 * (1/2) = 30 ;
b₃ = 60 * (1/2)² = 60 * 1/4 = 15 ;
b₄= 60* (1/2)³ = 60*1/8 = 7,5
s.a.m.d.