For the following geometric sequence find the explicit formula: {-1, 3, -9, ...}. an = -3 · an - 1 where a1 = -1 an = (-3) n - 1 an = -3 · an - 1 where a1 = 1 an = -1 · (-3) n - 1

The random variable x has probability density function f (x) = k(−x²+5x−4) 1 ≤ x ≤ 4 or =0 1 show that k = 2/9 find 2 e(x), 3 the mode of x, 4 the cumulative distribution function f(x) for all x. 5 evaluate p(x ≤ 2.5). 6 deduce the value of the median and comment on the shape of the distribution.