diketahui barisan aritmatika dengan suku ke 5 adalah 25. jumlah suku ke 8 dan 10 adalah 82. nilai suku ke 3 adalh

U5 : a + 4b = 25
a = 25 - 4b

U8 + U10 = 82
a + 7b + a + 9b = 82
2a + 16 b = 82
a + 8b = 41
25 - 4b + 8b = 41
4b = 41 - 25
4b = 16
b = 16/4
b = 4

a = 25 - 4b
a = 25 - 4(4)
a = 25 - 16
a = 9

U3 = a + 2b
U3 = 9 + 2(4)
U3 = 9 + 8
U3 = 17

U5 = 25
U8+U10 = 82

U5 = a+4b = 25 => a = 25-4b
U8+U10 = a+7b+a+9b = 82
U8+U10 = 2a+16b = 82

a = -4b+25

2a+16b = 82
2(-4b+25)+16b = 82
-8b+50+16b = 82
8b+50 = 82
8b = 82-50
8b = 32
b = 4

a = -4b+25
a = -4(4)+25 = -16+25 = 9

a = 9
b = 4

U3 = a+2b = 9+2(4) = 9+8 = 17

semoga membantu yaa:)