Question

Tolong dong yang nomor17

Answer 1

S9 =  (2a + 8b) = 45
=> 9a + 36b = 45
=> a + 4b = 5

S5 =  (2a + 4b) = 20
=> 5a + 10b = 20
=> a + 2b = 4

a + 4b = 5
a + 2b = 4
--------------- -
2b = 1 => b =

a + 2b = 4
=> a + 2() = 4
=> a = 3

jadi suku pertama = 3