Tuliskan lima suku pertama barisan artimetika apabila diketahui U5= 30 dan U10= 50.

U10 = a + 9b = 50
U5 = a + 4b = 30

eliminasi a 
5b = 20
b = 4

U5 = a + 4b = 30
a + 4(4) = 30
a = 30 – 16 = 14

U1 = 14 
U2 = 14 + 4 = 18
U3 = 14 + 2.4 = 14 + 8 = 22
U4 = 14 + 3.4 = 14 + 12 = 26
U5 = 14 + 4.4 = 14 + 16 = 30

U5 = a+4b = 30
U10 = a+9b = 50
U10 – U5
4b = 20
b = 20 : 4
b = 5
masukkan b=5 ke U5
a+4b=30
a+20=30
a= 30-20
a= 10
U1 = a = 10
U2= a+b = 10+5 = 15
U3= a+2b = 10+10= 20
U4= 25
U5= 30