Question

If x + y = 6 and xy = 5, find the value of x3 + y3.​

Answer 1

Step-by-step explanation:

$x {}^{3} + y {}^{3} \\ = (x + y) {}^{3} - 3xy(x + y) \\ = (6) {}^{3} - 3 \times 5 \times 6 \\ = 216 - 90 \\ = 126$

Answer 2

Given that:

• (x + y) = 6
• xy = 5

To Find:

• x³ + y³

Solution:

In order to find x³ + y³,

we know that :

• (x + y)³ = x³ + y³ +3xy(x + y)

Put value:-

(x + y)³ = x³ + y³ +3xy(x + y)

→ 6³ = x³ + y³ +3×5(6)

→ 216 = x³ + y³ + 90

→ x³ + y³ = 216 - 90

→ x³ + y³ = 126