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Question -

Find the maximum and minimum values, if any, of thefollowing functions given by

(i) f(x) = |x +2| − 1 (ii) g(x) = − |x + 1| + 3

(iii) h(x) = sin(2x)+ 5 (iv) f(x) = |sin 4x + 3|

(v) h(x) = +4, x (−1, 1)



Answer -

(i) f(x)= 

We know that for every x  R.
Therefore, f(x) =  for every x  R.
The minimum value of f is attainedwhen .
Minimum value of f = f(−2)

Hence, function f does nothave a maximum value.

(ii) g(x) =
We know that for every x  R.
Therefore, g(x) =  for every x  R.
The maximum value of g is attainedwhen
Maximum value of g = g(−1)= 

Hence, function g does nothave a minimum value.

(iii) h(x) = sin2x +5

We know that − 1 ≤ sin 2x ≤ 1.

− 1 + 5 ≤ sin 2x + 5 ≤ 1 + 5

4 ≤ sin 2x + 5 ≤ 6

Hence, the maximum and minimum valuesof h are 6 and 4 respectively.

(iv) f(x) =

We know that −1 ≤ sin 4x ≤ 1.

2 ≤ sin 4+ 3 ≤ 4

2 ≤≤ 4

Hence, the maximum and minimum valuesof are 4 and 2 respectively.

(v) h(x) = x +1, x  (−1, 1)

Here, if a point x0 isclosest to −1, then we find  for all x0  (−1, 1).
Also, if x1 isclosest to 1, then   for all x1  (−1, 1).

Hence, function h(x) hasneither maximum nor minimum value in (−1, 1).

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