Question

Carilah jumlah untuk tiap deret berikut
a.2+4+6+...+100
b.1+3+5+...+21
c.15+12+9...-36

Answer 1

A)Diketahui: a/u1=2 b=2 Un=100
Ditanya: Sn=?

100 = 2 + (n-1)2
100 = 2 + 2n - 2
100 = 2n
50 = n

Sn = n [(U1+Un)/2]
Sn = 50 [(2+100)/2]
Sn = 50 [102/2]
Sn = 50x51 = 2550

b) dan c) caranya sama selamat belajar!

b) d

Answer 2

A. sn= n/2 (2a+(n-1)b)
=100/2 (2.2+(100-1)2)
=50 (4+198)
=50 (202)
=10100
b. sn=n/2 (2a+(n-1)b)
=21/2 (2.21+(21-1)2)
=21/2 (42+40)
=21/2 (82)
=21× 41
=861
c. 1512