Question

if x+y =-4 find x³+y³-12xxy+64=0

Answer 1

x³+y³-12xxy+64=0
given, 
x+y =-4
we know that 
x³+y³= (x+y)² - 3xy(x+y)
∴ it can be written as 
(x+y)² - 3xy(x+y)-12xy +64
putting da values of x+y=-4 we get
(-4)³-3xy(-4)-12xy+64
= 0