suku ke-19 barisan aritmatika 0,2 0,6 1,0 1,4 ...adalah

a=0.2
b=0.4

un=a+(n-1)b
=0.2+(n-1)0.4
=0.2+0.4n-0.4
=0.4n-0.4-0.2
=0.4n-0.6

u19=0.4(19)-0.6
=7.6-0.6
=7