Geometric Progresssion

$Simple\\ \qquad \qquad Odd\quad terms\quad are\quad negative\\ and\quad \quad Even\quad terms\quad are\quad positive\\ So,\quad \\ \qquad The\quad answer\quad should\quad be\\ \qquad \qquad \qquad \boxed { 2 }$

it is alternating progression not geometric...

haha its just alternative -2,2,-2 and so on

Tn = a*r^(n-1)

where a is the first term and r is the common ratio.

here a=-2 and r=-1

T22 = (-2)*(-1)^(21) = (-2) * (-1) = 2