Question

Factorise : $(8a)^3/27 - b^3/8$

Answer 1

$(8a)^3/27 - b^3/8$

= $((2a)/3)^3 - (b/2)^3$

= $( (2a)/3 - b/2 )[((2a)/3)^2 + (2a)/3 xx b/2 + (b/2)^2 ]$

[ a3 - b3 = ( a - b )( a2 + ab + b2 )]

= $( (2a)/3 - b/2 )[ (4a)^2/9 + (ab)/3 + b^2/4 ]$