Question

biet hieu va tich 2 so deu la 1, the thi lap phuong cua chung la gi ? giup minh nhanh len nhe

Answer 1

Ta có

(x-y)=1 => (x-y)²=1

xy=1 => 4xy=4

=> (x-y)²+4xy=1+4

x²-2xy+y²+4xy=5

(x+y)²=5

=> x+y=\(\sqrt{5}\)

=>(x+y)³=5\(\sqrt{5}\)

=>x³+y³+3xy(x+y)=5\(\sqrt{5}\)

=>x³+y³+3.1.\(\sqrt{5}\) =5\(\sqrt{5}\)

=>x³+y³=2\(\sqrt{5}\)

Answer 2

1