Question

aflati termenul 100 din sirul 77 82 87 92 .........

Answer 1

an = a₁ + (n - 1) · r

a₁ = 77 ; ratia este 82-77 = 5; 87 - 82 = 5

a₁₀₀ = a₁ + (100 - 1) · r

a₁₀₀ = 77 + 99· 5

a₁₀₀ = 572

Answer 2

sirul : 77; 82; 87; 92; ...

T1 = 77 = 5 × 1 + 72

T2 = 82 = 5 × 2 + 72

T3 = 87 = 5 × 3 + 72

T4 = 92 = 5 × 4 + 72
...........
Tn = 5 × n + 72

T100 = 5 × 100 + 72 = 500 + 72 = 572
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