1kubik+2kubik+3kubik+.....................+15 kubik= n Jawaban n adalah.. (dengan rumus

1+2+3+4......+15 = n

a = 1
b = 1

s15 = n/2(a+un)
= 15/2 (1+15)
=15/2 . 16
= 15 . 8
= 120 kubik