Question 2769
 
 
    Before solving any problem on factorisation, one must know all the formulae by heart.  Here, 

    {{{a^3 - b^3}}} = {{{(a - b)(a^2 + ab + b^2)}}}
 
    {{{125x^3 - y^3}}}  =  {{{(5x)^3 - y^3}}}
 
 =  {{{(5x - y)((5x)^2 + 5xy + y^2)}}}    Answer.
     


gsm.