Let x be the edge  of the cube and v the volume respectively. We know that the edge of the cube is increasing at 3 cm/sec.We have to calculate that how fast it would increase when the edge is 10 cmLet us find dv/dt when x =10 cmNow, Volume =(Edge)3V=X3Now dv/dt=d(x)3/dtdv/dt=d(x)3/dt x dx/dxdv/dt=d(x)3/dt x dx/dtdv/dt=3x2x . dx/dtdv/dt=3x2x3……………………….(1)dv/dt=9x2Now when x=10 Then dv/dtx=10=9(10)2dv/dtx=10=900Since volume has to be in cm3/sec dv/dt=900 cm3/sec