If [math]a,b, c \gt 0[/math] and [math]abc=1[/math], how can I prove that [math](a+2) (b+3) (c+6) \ge 48?[/math] How does one prove for [math]a,b,c \ge 0[/math] that [math]a^3+b^3+c^3 \ge 3abc[/math]?