Question

11 и 12 задание .Помогите пожалуйста

Answer 1

Решение на фото........

Answer 2

$11) a_1 = -8; a_2 = -1; a_3 = 6...\d = a_2 - a_1 = -1 + 8 = 7\a_n = a_1 + d(n-1)\a_{51} = a_1 + d(50)\a_{51} = 342\12) (frac1{4a}+ frac1{8a})*frac{a^2}2 = frac{3a^2}{16a} = -frac{3*1.6}{16} = -0.3$