Page 7 - DIGITAL BOOK MUHAMMAD AZWARDI NASUTION

) (U −
) ....+
S = a + (a + ) b + (a + 2 b + (U − 2 b + n b + n
) U
n
n
S = U + (U − b + n 2 b + (a + 2 b + b + +
) (U −
) ....+
) (a +
) a
n
n
n
2 S = n (a + Un )
n
1
S = n (a + Un )
n
2

Rumus jumlah n suku pertama Deret Aritmetika

1
S = n (a + Un )
n
2  

1

atau S = n  a + a + (n − 1 )b 

n
2    
 U n 

1
S = n  a2 + (n − 1 )  b
n
2