If the equations x^2+bx-1 = 0 and x^2+x+b = 0 have a common root different from -1, then |b| is equal to:

JEE Main 2016 Mathematics question

If the equations and have a common root different from , then is equal to:

Answer: (3)

Subtracting the two equations eliminates and gives the common root directly:

(bx-1) - (x+b) = 0 ⇒ (b-1)x = 1+b ⇒ x = (b1).

Substituting this into and clearing denominators by multiplying through by :

(1+ + (1+b)(b-1)

Create a free account to read the complete working (5 steps), and practise questions like this in a timed test.

Question ID VK-115554