Find the solution set of the inequation |x – 1| < 2.

|x – 1| < 2


Square both sides


(x – 1)2 < 4


x2 – 2x + 1 < 4


x2 – 2x – 3 < 0


x2 – 3x + x – 3 < 0


x(x – 3) + 1(x – 3) < 0


(x + 1)(x – 3) < 0


Observe that when x > 3 (x – 3)(x + 1) is positive


And for each root the sign changes hence



We want less than 0 that is negative part


Hence x should be between -1 and 3 for (x – 3)(x + 1) to be negative


Hence x (-1, 3)


Hence solution set for |x – 1| < 2 is (-1, 3)


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