tentukan suku pertama,beda,dan suku ke-10 dari barisan berikut !! a.1,3,5,7,........ b.5,2,-1,-4,...

a. U1 = 1 beda = 2 
==> U10 = U1 + (10-1)b
==> U10 = 1 + 9.2
==> U10 = 1 + 18
==> U10 = 19

b. U1 = 5 beda = -3
==> U10 = U1 + (10-1)b
==> U10 = 5 + 9.(-3)
==> U10 = 5 + (-27)
==> U10 = -22

semoga membantu ^_^