1+3+5+7+...+1997=...

Materi : Barisan dan Deret
Kelas : IX SMP

1 + 3 + 5 + 7 + ... + 1997 = ?

Step 1 :
◆◆◆◆◆◆

Cari dulu "banyak suku ke - n" :
》Un = U1 + ( n - 1 ) b
》1997 = 1 + (n - 1 )2
》1997 = 1 + 2n - 2
》1997 = 2n - 1
》1997 + 1 = 2n
》1998 = 2n
》999 = n

Step 2 :
◆◆◆◆◆◆◆

Cari "Jumlah suku ke - n pertama " :
》Sn = n/2 ( 2.U1 + (n - 1) b )
》S999 = 999/2 ( 2.1 + (999 - 1 ) 2)
》S999 = 449,5 ( 2 + 998 × 2)
》S999 = 499,5 ( 2 + 1996 )
》S999 = 499,5 ( 1998 )
》S999 = 998.001

Salam ...