Question

If x = 1 is a common root of ax² + ax + 2 = 0 and x² + x + b = 0 then, ab = 

A. 1 

B. 2 

C. 4 

D. 3

Answer 1

Since x = 1 is root of equation 

Then it satisfy the equation 

Putting x = 1 in first equation 

a + a + 2 = 0 

2a + 2 = 0 a = – 1 

Putting x = 1 in equation second 

1 + 1 + b = 0 

2 + b = 0 

b = – 2 

ab = – 1 x – 2 

ab = 2