tentukan suku pertama (a) beda(b) dan suku ke 30 dan setiap barisan berikut B. 35,31,27,25.... C.100,95,90,85.....

B. 35,31,27,25

a = 35 (suku pertama)
b = U2 - U1 = 31 - 35 = -4
U30 = a + (n-1)b
= 35 + (30 -1)-4
=35+ (29)-4
=35 - 116
= -81


C. 100,95,90,85

a = 100 ( suku pertama)
b = U2 - U1 = 95 - 100 = -5
U30 = a + (n-1) b = 100 + (30-1) -5
= 100 + (29)-5
= 100 - 145
= -45