Odpowiedź:
a₁ = 2
a₂ = a + 4
a₆ = a₁ + 5r = 2 + 5r = 9 1/2
5r = 9 1/2 - 2 = 7 1/2
r - różnica ciągu = 7 1/2 : 5 = 15/2 * 1/5 = 3/2 * 1 = 1 1/2
a₂ = a₁ + r = 2 + 1 1/2 = 3 1/2
a + 4 = 3 1/2
a = 3 1/2 - 4 = 3 1/2 - 3 2/2 = - 1/2
Odp: a = - 1/2
sprawdzenie
a₂ - a₁ = r
3 1/2 - 2 = 1 1/2
1 1/2 = 1 1/2
L = P
