Suatu barisan aritmatka diketahui u3=13 u7=33.suku ke 51 adalah

Aritmatika
Un = a + (n-1)b

U3 = 13
U3 = a + 2b
a + 2b = 13

U7 = 33
U7 = a + 6b
a + 6b = 33

eliminasi

a + 6b = 33
a + 2b = 13 (-)
--------------------
4b = 20
b = 20/4
b = 5

a + 2b = 13
a + 2(5) = 13
a + 10 = 13
a = 13 - 10
a = 3

U51 = a + 50b
= 3 + 50(5)
= 3 + 250
= 253

U3 = a + 2b = 13
U7 = a + 6b = 33
------------------------ -
-4b = -20
b = 5
a + 2b = 13
a + 2(5) = 13
a + 10= 13
a = 13-10
a = 3
rumus mencari suku
U51 = a + 50b
= 3 + 50 (5)
= 3 + 250
= 253