dketahui (m+1),2m,41 merupakan 3 suku berurutan aritmatika. tentukan bedanya

Kelas 8 Matematika
Bab Barisan dan Deret Bilangan

2 . U2 = U1 + U3
2 . 2m = m + 1 + 41
4m - m = 42
3m = 42
m = 42/3
m = 14

b = U3 - U2
b = 41 - 2m
b = 41 - 2 . 14
b = 41 - 28
b = 13

U1 = m + 1

U2 = 2m

U3 = 41


Menentukan beda barisan :

b= U2 - U1
b= 2m - (m + 1)
b= m - 1................. (1)


b= U3 - U2
b= 41 - 2m


Maka,

m - 1 = 41 - 2m

m + 2m = 41 + 1

3m = 42

m = 42/3

m = 14



Maka,
U1 = m + 1 = 14 + 1 = 15

U2 = 2m = 2(14) = 28


Maka, beda barisan :

b = U2 - U1

b = 28 - 15

b = 13 ✔