Question

If (x + y) = 7 and xy = 2, find the value of x^3+y^3

Answer 1

Answer: 301

Step-by-step explanation:

$x^{3} + y^{3} = (x + y) (x^{2} -xy + y^{2})$ = $(x + y) [(x^{2} + 2xy + y^{2}) - 3xy]$

            = $(x + y) [ (x+y)^{2} - 3xy]$

            = (7) [(7)^2 - 3(2)] = 7 x (49 - 6) = 7x 43 = 301

Answer 2

Answer:

(x^3 + y^3)=301

Step-by-step explanation:

(x+y)=7  &  xy=2

x^3 + y^3

(x+y)^3 = (x^3 + y^3) + 3xy (x+y)

(7)^3 = (x^3 + y^3) + 3X2 (7)

343 = (x^3 + y^3) + 6X7

343 = (x^3 + y^3) + 42

343-42 = (x^3 + y^3)

301 = (x^3 + y^3).