Дана арифметическая прогрессия (bn):−2; −5; −8…
Найдите b12.

b₁ = - 2

b₂ = - 5

b₂ = b₁+ d

d = b₂ - b₁ = - 5 - (- 2) = - 5 + 2 = - 3

b₁₂ = b₁ + 11d = - 2 + 11 * (- 3) = - 2 - 33 = - 35

ответ : b₁₂ = - 35

(-2+ - 5(-2) + 25)) + 2(-2^2+3) = 3^(-4-7+25) +2(-4+3) = 3^(-11+25) + 2(-1) = 3^14+2^(-1) = 42+(-2) = 40

z^3+3z=-7z^2-21=

=z(3+z^2)=-7(3+z^2)=

=(z-7)(3+z^2)