Question

find value of 27x^3+8y^3 if 3x+2y=14 and xy= 8

Answer 1

3x+2y = 14

cube on both sides,

(3x+2y)^2 = 14^3

= 27x^3 +8y^3 +3(3x*2y)[3x+2y] = 2744

=27x^3 + 8y^3 + 18(8)[14] = 2744

=27x^3 + 8y^3 + 2016 = 2744

 = 27x^3 +8y^3 = 2744 - 2016

=27x^3 +8y^3 = 728




i hope this will help you 




- by ABHAY

Answer 2

27x³+8y³= (3x)³ + (2y)³
= (3x+2y)³-3(3x*2y)(3x+2y)
= (14)³-3(6*8)(14)
= 2744 - 2016
= 728