Question

which sequence is geometric                                                                                               A 5 15 25 35        B 5 10 25 35   C 6 12 18 24    D 7 14 21 28

Answer 1

If a, b, c, d is geometric sequence, then

$\dfrac{b}{a}=\dfrac{c}{b}=\dfrac{d}{c}=const.$

A. 5; 15; 25; 35

$\dfrac{15}{5}=3;\ \dfrac{25}{15}=\dfrac{5}{3}-NOT$

B. 5; 10; 25; 35

$\dfrac{10}{5}=2;\ \dfrac{25}{10}=\dfrac{5}{2}-NOT$

C. 6; 12; 18; 24

$\dfrac{12}{6}=2;\ \dfrac{18}{12}=\dfrac{3}{2}-NOT$

D. 7; 14; 21; 28

$\dfrac{14}{7}=2;\ \dfrac{21}{14}=\dfrac{3}{2}-NOT$

Answer: None of the sequences is a geometric series.