Question

if 2x+3y=13 and xy=6 find 8x^3+27y^3

Answer 1

Given, 2x + 3y = 13   ------------- (1)

        Cubing on both sides, we get

        (2x + 3y)^3 = (13)^3

       (a+b)^3 = a^3+b^3 + 3ab(a+b)

      (2x)^3 + (3y)^3 + 3(2x)(3y)(2x + 3y) =2197

      8x^3 + 27y^3 + 18xy(13)= 2197

      8x^3 + 27y^3 + 18(6)(13)= 2197

      8x^3 + 27y^3 = 2197 - 1404

       8x^3 + 27y^3 = 793


Hope this helps!

Answer 2

Answer is in attachment.
8x^3+27y^3=793