Barisan aritmatika 7,11,15,………, 131.Bagaimana suku barisan tersebut adalah… ​

Jawaban:

Diket = a= 7

b= 4

un= 131

Un = a + (n-1)b

= 7 + (n-1) 4

= 7 + 4n – 4 = 131

4n = 131-7+4

4n =128

n = 128/4

n = 32

Jumlah deret aritmatikanya =

Sn = n/2 (2a+(n-1)b

S32 = 32/2 (2(7)+(32-1)4

=16.(14+124)

=16.138

= 2208