Given that equation ax^2 + bx + c = 0 has roots α and β
=> α + β = -b/a
and αβ = c/a
/(aα + b) + 1/(aβ + b)
We already know that
α + β = -b/a
=> a(α + β) = -b
=> -a(α + β) = b
Substituting this value of b in the problem,
=> 1/(aα + b) + 1/(aβ + b)
=> 1/(aα - a(α + β)) + 1/(aβ - a(α + β))
=> 1/(-aβ) + 1/(-aα)
=> -1/a (1/β + 1/α)
=> -1/a (α + β)/αβ
=> -1/a (-b/a)(c/a)
=> b/ac