Question

Which of these is a geometric sequence ?

Answer 1

Its B because each term after the first is obtained by multiplying the previous term by a constant value of 2

for example 1/4 * 2 = 1/2 and 1/2 * 2 = 1 and so on...

Answer 2

`\text{If}\ a_1;\ a_2;\ a_3;\ ...;\ a_n\ \text{is a geometric sequence, then}\ (a_n)/(a_(n-1))=const.`



`A.\\1;\ 5;\ 9;\ 13;\ ...\\\\(5)/(1)=5\\(9)/(5)\\eq5\\\\B.\\(1)/(4);\ (1)/(2);\ 1;\ 2;\ 4;\ ...\\\\((1)/(2))/((1)/(4))=(1)/(2)\cdot(4)/(1)=2\\(1)/((1)/(2))=1\cdot(2)/(1)=2\\(2)/(1)=2\\(4)/(2)=2\\\text{the geometric sequence}`

`C.\\2;\ 3;\ 5;\ 9;\ 17;\ ...\\\\(3)/(2)=1.5\\(5)/(3)\\eq1.5\\\\D.\\3;\ -15;\ -33;\ -51;\ -69;\ ...\\\\(-15)/(3)=-5\\\dfraxc{-33}{-15}=(11)/(5)\\eq-5\\\\\boxed{\text{Answer is B.}}`