1.

Find the domain of the following functions.fx = \(\sqrt{log(x^2-6x+6)}\)fx = √log(x2 - 6x +6)

Answer»

 f(x) = \(\sqrt{x-x^2} + \sqrt {5-x}\)

For f to be defined, 

log (x2 – 6x + 6) ≥ 0 

∴ x2 – 6x + 6 ≥ 1 

∴ x2 – 6x + 5 ≥ 0

∴ (x – 5)(x – 1) ≥ 0 

∴ x ≤ 1 or x ≥ 5 …..(i) 

[∵ The solution of (x – a) (x – b) ≥ 0 is x ≤ a or

x ≥ b, for a < b]

and x2 – 6x + 6 > 0 

∴ (x – 3)2 > -6 + 9 

∴ (x – 3)2 > 3 

∴ x < 3 – √3 0r x > 3 + √3 ……..(ii) 

From (i) and (ii), we get 

x ≤ 1 or x ≥ 5 

Solution set = (-∞, 1] ∪ [5, ∞) 

∴ Domain of f = (-∞, 1] ∪ [5, ∞)



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