найдите первые 6 членов геометрической прогрессии (bn), если: а) b1 = - 1, q = 3 б) b1 = - 2, q = - 1/2

Как известно общий член геометрической прогресс bn определяется по формуле:

bn = b1 * q^ (n - 1), определим b1, b2, b3, b4, b5, b6.

а) b1 = - 1, q = 3, b2 = b1 * q^ (2 - 1) = b1 * q = (-1) * 3^1 = 3,

b3 = b1 * q^2 = - 1 * (3^2) = - 9,

b4 = b1 * q^3 = - 1 * 3^3 = - 27,

b5 = b1 * q^4 = - 1 * 3^4 = - 81,

b6 = b1 * q^5 = - 1 * 3^5 = - 243.

б) b1 = - 2, q = - 1/2,

b2 = b1 * q^1 = (-2) * (-1/2) ^1 = 2/2 = 1,

b3 = b1 * q^2 = (-2) * (-1/2) ^2 = - 2/4 = - 1/2,

b4 = b1 * q^3 = (-2) * (-1/2) ^3 = - 2 / (-8) = 1/4,

b5 = b1 * q^4 = (-2) * (-1/2) ^4 = - 2/16 = - 1/8,

b6 = b1 * q^5 = (-2) * (-1/2) ^5 = - 2 / (-32) = 1/16.