suatu barisan arimatika diketahui suku ke7=100 dan suku ke15=172 tentukan suku ke 10

u7 = a + 6b = 100
u15 = a + 14b = 172

eliminasi a
-8b = -72
b = 9

subtitusi b
a + 6b = 100
a + 6(9) = 100
a + 54 = 100
a = 100 -54
a = 46

u10 = a + 9b = 46 + 9(9) = 46 + 81 = 127

U15=172--->a+14b = 172
U7=100 - - - >a+6b=100
8b = 72
b=9
a+6b=100
a+6(9)=100
a+54 =100
a = 46
U10 = a+9b = 46 + 9(9) = 46 + 81 = 127