dari barisan 3,7,11,15.tentukanlah a.u20 b.s20
Matematika
geylang67
Pertanyaan
dari barisan 3,7,11,15.tentukanlah a.u20 b.s20
2 Jawaban
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1. Jawaban BSunShine
Materi : Barisan dan Deret
Kelas : IX SMP
3 , 7 , 11 , 15 , .. , ...
U1 = 3
b = 4
Un = U1 + (n - 1)b
U20 = 3 + 19 ( 4)
U20 = 3 + 76
U20 = 79
Sn = n/2 ( 2 . U1 + (n - 1) b)
S20 = 20/2 ( 2. 3 + 19 ( 4 ))
S20 = 10 ( 6 + 76 )
S20 = 10 ( 82 )
S20 = 820 -
2. Jawaban AngieJune16
Un = a+(n-1) x b b = u2-u1 = 7-3 = 4
Sn = n/2 (2a+(n-1) x b)
U20 = 3+(20-1) x 4
U20 = 3+ 19x4
U20 = 3 + 76 = 79
S20 = n/2 (2a+(n-1) x b)
S20 = 20/2 (2.3 + (20-1) x 4
S20 = 10 (6 + 19 x 4)
S20 = 10 (6+ 76)
S20 = 10 (82)
S20 = 820