Question

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

Answer 1

2x+3y= 13

cube on both sides,

(2x+3y)^3  = 13^3

8x^3 + 9y^3 + 3(2x*3y) [2x+3y] = 2197


8x^3 + 9y^3 + 18(xy)[13] = 2197

8x^3 + 9y^3 + (18*6*13) = 2197

8x^3 + 9y^3 + 1404 = 2197

8x^3 + 9y^3 = 2197- 1404

8x^3 + 9y^3 = 793


i hope this will help you



- by ABHAY

Answer 2

(2x+3y)=13. (2x+3y)^3=13^3. 8x^3+27y^3+3(2x×3y)+(2x+3y)=2197 8x^3+27y^3+3(6×6)+(13)=2197. (XY=6) 8x^3+27y^3+108=2197-13. 8x^3+27y^3=2184-108. 8x^3+27y^3=2076