Question

If quadratic equation 2x^2 + ax + b=0 , 2x^2 + bx + a=0 and ax^2 - x + 1=0 have common root, the value of a + b
(A) -3
(B) -2
(C) -1
(D) 0

Answer 1

Answer:

(B) -2

Step-by-step explanation:

2x^2+ax+b-(2x^2+bx+a)=0

(a-b) x+(b-a) =0

(a-b) (x-1)=0

a=b or x=1

but a≠b

ie x=1

ax^2-x+1=0 => a=0

substituting this on 1st eqn

2+b=0

b=-2

so a+b=0-2=-2