Question

Q-15 Find the value of x3+y3-12xy+64, when x+y=-4​

Answer 1

Answer:

This is according to your question........however I do think it should be +12xy instead of -12xy

In that case, answer would be 0

as 12xy and -12xy would get cancelled like 64 and -64

Answer 2

Step-by-step explanation:

Given

x + y = -4 => ①

x³ + y³ - 12 xy + 64 ====> (i)

Apply formula

(x + y)³ = x³ + y³ + 3xy ( x + y )

( - 4 )³ = x³ + y³ + 3xy ( - 4 )

- 64 = x³ + y³ - 12xy

- 64 + 12xy = x³ + y³ => ②

Apply ② in (i)

• x³ + y³ - 12xy + 64
• - 64 + 12xy - 12xy + 64

Cancel " -64 & +64 " and " +12xy & -12xy "

• 0

Therefore ,

x³ + y³ + 3xy ( x + y) = 0