Diketahui barisan aritmatika drngan U3=12 dan U9=36maka U10=....... beserta rumusnya

Rumus suku ke-n barisan aritmatika = Un = a + (n-1) b
U3 = a + (3-1) b  => 12 = a + 2 b
U9 = a + (9-1) b  => 36 = a + 8 b
                               ___________-
                                -24 = -6 b
                                  4  = b
=> a + 2 b  = 12
=> a+ 2 (4) = 12
=> a + 8      = 12
=> a            = 4

=> U10 = a + (10-1) b
=> U10 = 4 + (9) 4
=> U10 = 4 + 36
=> U10 = 40