Question

30. If x + y = 6 and xy = 11, find the value of x^3+y^3
please answer the question fast​

Answer 1

Answer: 18

Solution:

Given that,

• x + y = 6
• xy = 11

We are required to find the value of ( x³ + y³ )

Now we are aware of the identity:

→ ( x + y )³ = x³ + y³ + 3xy ( x + y )

Therefore on transposing 3xy ( x + y ) from RHS we get:

→ ( x + y )³ - 3xy ( x + y ) = x³ + y³

Using the given information and substituting it, we get:

→ ( 6 )³ - 3 ( 11 ) ( 6 ) = x³ + y³

→ 216 - 33 ( 6 ) = x³ + y³

→ 216 - 198 = x³ + y³

→ x³ + y³ = 18

Therefore the value of ( x³ + y³ ) is 18.