(Tolong bantu rumus) 1. selisih pj 2 rusuk kubus 3dm. selisih luas sisi kubus 234dm, selisih volume ke 2 kubus tsb adalah?

R1 - r2 = 3 dm
r1 = 3 + r2
6 r1² - 6r2² = 234
6 (3 + r2)² - 6r2² = 234
6 (9 + 6r2 + r2²) - 6r2² = 234
54 + 36r2 + 6r2² - 6r2² = 234
36r2 = 234 - 54
36r2 = 180
r2 = 5
r1 = 3 + r2 = 8
V1 - V2 = 8³ - 5³
= 512 - 125
= 387