Question

If x + y = 4, then the value of (x³ + y³ + 12xy) is

• A. 64
• B. 16
• C. 4
• D. 256

Answer 1

Answer:

A. 64

Solution:

Given:

x + y = 4

Formula Used:

(x + y)³ = x³ + y³ + 3xy (x + y)

Calculation:

Here, x + y = 4

So, x³ + y³ + 12xy = x³ + y³ + 3xy $\times$ 4

⇒ x³ + y³ + 12xy = x³ + y³ + 3xy (x + y) = (x + y)³

⇒ x³ + y³ + 12xy = 4³

⇒ x3 + y3 + 12xy = 64

∴ The value of x3 + y3 + 12xy is 64.