2. Найдите сумму шести первых членов геометрической прогрессии:

a) S₆ = 3 * (1 - (-4)⁶) / (1 - (-4)) = 3 * (1 - 4096) / 5 = -2457.

в) S₆ = 3 * (1 - 3⁶) / (1 - 3) = 3 * (1 - 729) / (-2) = 3 * (-728) / (-2) = 1092.

б) S₆ = 4 * (1 - 0.2⁶) / (1 - 0.2) = 4 * (1 - 0.000064) / 0.8 = 5 * 0.999936 = 4.99968.

г) S₆ = √6 * (1 - (√6)⁶) / (1 - √6) = √6 * (1 - 216) / (1 - √6) = -215√6 / (1 - √6) = 215√6 / (√6 - 1) = 215 * 6 / (6 - √6) = 1290 / (6 - √6) = 1290 * (6 + √6) / (36 - 6) = 1290 * (6 + √6) / 30 = 43 * (6 + √6) = 258 + 43√6.