Tolong dong no 4 itu..

rusuk kubus I  = s
rusuk kubus II = s-4

volume kubus I  = s³
volume kubus II = (s-4)³

                    Selisih vol kubus = 208
                               s³ - (s-4)³  = 208
s³- [s³+3s²(-4)+3s(-4)²+1(-4)³] = 208
s³- [s³-  12s²   +48s     - 64    ] = 208
                         12s²-48s-144 = 0
                        ---------------------------- : 12
                              s² -4s - 12 = 0
                              (s-6)(s+2) = 0
 s = 6 atau s = -2

 rusuk kubus I  = 6 cm
 rusuk kubus II = 6-4 = 2 cm

a) vol kubus I  = 6³ = 216 cm³
    vol kubus II = 2³ = 8 cm³

b) Lp kubus    = 6s²
    Lp kubus I  =  6.6² = 216 cm²
    Lp kubus II =  6.2² = 24 cm²

c) L diagonal bidang = s²√2
              Ldb kubus I = 6²√2 = 36√2 cm²
            L db kubus II = 2²√2 = 4√2 cm²