Question

Jika diketahui barisan aritmatika memiliki U3 = 41 dan U6 = 65 maka U7 adalah..............?​

Answer 1

Jawab:

U7 = 83

Penjelasan dengan langkah-langkah:

U3 = 41

U6 = 65

Un = a + (n-1)b

41 = a + (3-1)b = a + 2b ... (i)

65 = a + (6-1)b = a + 5b ... (ii)

Persamaan (i) disubstitusi ke persamaan (ii)

a = 41 - 2b

65 = a + 5b = (41 - 2b) + 5b = 41 +3b

65 = 41 + 3b

3b = 65 - 41 = 24

b = 24/3 = 8

a = 41 -2b = 41 - (2*8) = 41 - 16 = 35

U7 = a + (n-1)b = 35 + (7-1)8 = 35 + 48 = 83