Question

if x +2y=6 then find the value of x³- 8y³ -36xy- 216

Answer 1

Answer:

Step-by-step explanation:

x+2y=8……….(1). and. x.y=6………….(2)

From eqn. (1)

(x+2y)^3=(8)^3

or. x^3+(2y)^3+3.x.2y.(x+2y)= 512.

or. x^3+8y^3+6.xy.(x+2y)= 512.

Putting x+2y=8 from eqn. (1) and xy= 6 from eqn. (2)

or. x^3+8y^3+6.6.8=512

or. x^3+8y^3=512–288. = 224. Answer.