If , then the value of  is

• 7

• 11

• 23

• 27

If  and  ,  then the value of  is

• 0

• 1

• -1

• 2

If x = at² and y = 2at then

• x² = 4ay

• y² = 4ax

• x² + y² = a²

• x² - y² = a²

If xy + yz + zx = 1,   then the value of  is

• 2

• 3

• 4

• 1

If  then  is equal to

If a + b = 3 then the value of a³ + b³ + 9ab - 27 is

• 24

• 25

• 0

• 27

If  then the value of  is equal to

• 0

• 1

• 2

• 3

If a = 11  and b = 9, then the value of  is

• 

• 2

• 

• 20

If , then x is equal to

If a and b be positive integers such that a² - b² = 19, then the value of a is

• 19

• 20

• 9

• 10