Question

If x-y = 3 ,xy =10 find the value of x^3-y^3 please tell me fast​

Answer 1

Given:

x-y = 3 and xy = 10

To find: x^3- y^3

x-y = 3 ......equ(1)

(x-y)^2 = 9

or, x^2 + y^2 -2xy = 9

or, x^2 + y^2 - 20 = 9

or, x^2 + y^2 = 29 ..... equ(2)

from identity,

x^3 - y^3 = (x-y)(x^+xy+y^2)

using equations 1 & 2

x^3 - y^3 = 3(29 +10)

or, x^3 - y^3 = 3(39)

or, x^3 - y^3 = 117