Sonli ketma-ketliklar va arifmetik progressiya
Javoblar ota-onalar va o‘qituvchilar uchun.
1
a_n = n² + 2 ketma-ketlikning dastlabki to‘rtta hadini yozing.
3, 6, 11, 18
2
a₁ = 3, a_(n+1) = 2a_n − 1 bo‘lsa, a₂, a₃, a₄ ni toping.
5, 9, 17
3
5, 9, 13, ... progressiyaning a₁₀ hadini toping.
41
4
Arifmetik progressiyada a₄ = 14, a₉ = 39 bo‘lsa, d va a₁ ni toping.
d = 5, a₁ = −1
5
a_n = 4 − 3n ketma-ketlik arifmetik progressiya ekanini isbotlang va d ni toping.
a_(n+1) − a_n = (4 − 3(n + 1)) − (4 − 3n) = −3, demak d = −3.