Posted by Alisha on Monday, November 28, 2011 at 6:06pm.
Note that 1) 8x^3+27y^3 ≡ (2x)^3+(3y)^3 and apply the following identity: a^3+b^3 = (a+b)(a^2-ab+b^2) hint: substitute a=2x, b=3y 2) same strategy as the first.