Shashwat Srivastava

CAT Preparation Community 9y ago

value of the expression (x^2 - x + 1)/(x - 1) cannot lie between a) 1,-3 b) -1,-3 c) -4,2 d) -4,-2

2

Maruti KonduriFaculty 9y ago

Let (x^2 - x + 1)/(x-1) = k
Therefore, x^2 - x + 1 = kx - k
Or, x^2 - (k+1)*x + (k+1) = 0

For this equation to have real roots, the discriminant should be greater than zero.
So, (k+1)^2 >= 4*(k+1)
Or, (k+1)(k-3) >= 0

Therefore, k can't lie between (-1,3)

Take a look at this formula sheet for CAT, it might be useful for you.

Parth Savla 6y ago

Why k+1

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