bantu dong PR matematika No a

2 , 8 , 14 , 20 , ...
a = 2
b = 8 - 2 = 6

Un = a + (n - 1)b
U₂₀ = a + 19b
U₂₀ = 2 + 19(6)
U₂₀ = 2 + 114
U₂₀ = 116

Sn = n/2 (2a + (n - 1)b)
S₁₀ = 10/2 (2(2) + 9(6))
S₁₀ = 5 (4 + 54)
S₁₀ = 5 (58)
S₁₀ = 290