Question

ifx/y +y/x = -1(x,y not equal to 0 ) , the value of x3 -y3 is ​

Answer 1

Solution :

Given : x/y + y/x = - 1

⇒ (x² + y²)/(xy) = - 1

⇒ x² + y² = - xy

⇒ x² + y² + xy = 0

∴ x³ - y³

= (x - y) (x² + y² + xy)

= (x - y) * 0

= 0 ,

which is the required value.

Identity Rules :

• (a + b)² = a² + 2ab + b²
• (a - b)² = a² - 2ab + b²
• a² + b² = (a + b)² - 2ab
• a² - b² = (a + b) (a - b)
• (a + b)³ = a³ + 3a²b + 3ab² + b³
• (a - b)³ = a³ - 3a²b + 3ab² - b³
• a³ + b³ = (a + b) (a² - ab + b²)
• a³ - b³ = (a - b) (a² + ab + b²)