a₁ = - 1 a₂ = 3
a₂ = a₁ + d
d= a₂ - a₁ = 3 - ( - 1) = 3 + 1 = 4
a₅ = a₁ + 4d = - 1 + 4 * 4 = - 1 + 16 = 15
a₅ = 15
a₁ = - 1 a₂ = 3
a₂ = a₁ + d
d= a₂ - a₁ = 3 - ( - 1) = 3 + 1 = 4
a₅ = a₁ + 4d = - 1 + 4 * 4 = - 1 + 16 = 15
a₅ = 15