Question

Identify the sequence 1, -1 , -3, -5, ......... is a AP or GP​

Answer 1

1st element = 1

checking GP

it should be,

$\frac{ - 1}{1} = \frac{ - 3}{ - 1}$

IT'S NOT TRUE ....

HENCE ITS NOT GP

checking AP

$1 - 2 = - 1 \\ \\ - 1 - 2 = - 3 \\ \\ - 3 - 2 = - 5$

HENCE ITS GP