Question

if x+y =9 and xy = 18,find the value of x^3 +y^3​

Answer 1

Answer:

Correct option is

C

189

We know that

x

3

+y

3

=(x+y)

3

−3xy(x+y)

so, x

3

+y

3

=(3)

3

−3(−18)(3)

=27+162

x

3

+y

3

=189

Answer 2

Answer:

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

(9)^3= x^3+y^3+3(18)(9)

729= x^3+y^3+486

x^3+y^3= 729- 486

x^3+y^3=243