Question

Suatu barisan bilangan memiliki rumus umum Un = an + b. Jika U11 = 52 dan U 13 = 63. maka nilai a + b adalah...
A. -3 C. 5
B. -2 D. 14
Tolong di Jawab ya... karna ini cth soal Ujian Mid

Answer 1

Verified answer

13a+b = 63
11a+b = 52
________-
2a = 11
a = 5,5

11a + b = 52
60,5 + b = 52
b = - 8,5

a+b = 5,5 - 8,5 = -3 (A)

Answer 2

Verified answer

Un = an + b
U11 = 11a + b = 52
U13 = 13a + b = 63
------------------- -
-2a = - 11
2a = 11
a = 5,5

11a + b = 52
11(5,5) + b = 52
60,5 + b = 52
b = 52 - 60,5
b = -8,5

a+b
= 5,5 + (-8,5)
= -3


Jawabannya yg A.