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

Answer:

b is the correct option

Answer 2

B. 2

Step-by-step explanation:

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

Substituting x = 1 in ax² + ax + 2 = 0, we get:

a + a + 2 = 0

2a = -2

a = -1 -----(1)

Substituting x = 1 in  x² + x + b = 0, we get:

1 + 1 + b = 0

b = -2 -----(1)

Now from 1 and 2, we get ab = -1 * -2 = +2

Option B is the answer.