Examine the following function for extreme values:f(x) = (x –

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 Multiple Choice QuestionsShort Answer Type

231.

Find the absolute maximum value and the absolute minimum value of the following functions in the given intervals:
straight f left parenthesis straight x right parenthesis space equals space left parenthesis straight x minus 1 right parenthesis squared plus 3 comma space space space space straight x space element of space space open square brackets negative 3 comma space space 1 close square brackets



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232.

Find the absolute maximum value and the absolute minimum value of
straight f left parenthesis straight x right parenthesis space equals space open parentheses 1 half minus straight x close parentheses squared space space plus space straight x space cubed space space space in space space space left square bracket negative 2 comma space space 2.5 right square bracket.

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 Multiple Choice QuestionsLong Answer Type

233.

Find the absolute maximum and minimum values of the function f given by
 f (x) = cos2x + sinx,  x ∊ [0, straight pi].

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234.

Find the points at which the function f given by f (x) = (x – 2)4 (x + 1 )3 has
(i) local maxima (ii) local minima (iii) point of inflexion .

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235.

Examine the following function for extreme values:
f(x) = (x – 3)(x + 1)6


Here f (x) = (x – 3)5 (x + 1)6
Differentiating (I) w.r.t. x, we get
f ' (x) = 5 (x – 3)4 (x + 1)6 + (x – 3)5 (x + 1 )5
∴   f ' (x) = (x – 3)4 (x + 1)5 [5 (x + 1) + 6 (x – 3)]
= (x – 3)4 (x + 1)(11 x – 13)
Now,   space straight f apostrophe left parenthesis straight x right parenthesis space equals space 0 space space space space space when space straight x space equals space 3 comma space space minus 1 space space of space 13 over 11
(a) When x = 3
If x < 3 (slightly), f ' (x) = (+) (+) (+) = + ve
If x > 3 (slightly), f ' (x) = (+) (+) (+) = + ve
Hence f ' (x) does not change sign as x passes through 3.
∴  x = 3 is neither a point of maxima, nor a point of minima. 3 is a point of inflexion.

(b) When x = – 1
If x < – 1 (slightly), f ' (x) = (+) (–) (–) = + ve
If x > – 1 (slightly), f ' (x) = (+) (+) (–) = – ve
∴  f ' (x) changes from positive to negative as a passes through – 1
Hence x = – 1 is a point of local maxima and maximum value of the function at x = – 1 is f (– 1) = 0.

(c) When straight x space equals space 13 over 11
  If space straight x less than 13 over 11 space left parenthesis slightly right parenthesis comma space space straight f apostrophe left parenthesis straight x right parenthesis space equals space left parenthesis plus right parenthesis thin space left parenthesis plus right parenthesis thin space left parenthesis negative right parenthesis space equals space minus ve comma
If space straight x greater than 13 over 11 left parenthesis slightly right parenthesis comma space space space straight f apostrophe left parenthesis straight x right parenthesis space equals space left parenthesis plus right parenthesis thin space left parenthesis plus right parenthesis thin space left parenthesis plus right parenthesis space equals space plus ve
therefore space space space space straight f apostrophe space left parenthesis straight x right parenthesis space changes space from space negative space to space positive space as space straight x space passes space through space 13 over 11
Hence space 13 over 11 space is space straight a space point space of space local space minimum space and space locla space minimum space value space is space given space by
space space space space space straight f open parentheses 13 over 11 close parentheses space equals space open parentheses 13 over 11 minus 3 close parentheses to the power of 5 space space open parentheses 13 over 11 plus 1 close parentheses to the power of 6 space equals negative fraction numerator left parenthesis 20 right parenthesis to the power of 5 over denominator left parenthesis 11 right parenthesis to the power of 5 end fraction fraction numerator left parenthesis 24 right parenthesis to the power of 6 over denominator left parenthesis 11 right parenthesis to the power of 6 end fraction space equals space fraction numerator 2 to the power of 28. end exponent 3 to the power of 6. space 5 to the power of 5 over denominator left parenthesis 11 right parenthesis to the power of 11 end fraction

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 Multiple Choice QuestionsShort Answer Type

236.

Find the local maxima or local minima, if any, of following functions using the first derivative test only. Find also the local maximum and the local minimum values, as the case may be:
The constant function straight alpha

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237.

Find the local maxima or local minima, if any, of following functions using the first derivative test only. Find also the local maximum and the local minimum values, as the case may be:
f(x) = x2

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238.

Find the local maxima or local minima, if any, of following functions using the first derivative test only. Find also the local maximum and the local minimum values, as the case may be:
straight x cubed minus 3 space straight x

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239.

Find the local maxima or local minima, if any, of following functions using the first derivative test only. Find also the local maximum and the local minimum values, as the case may be:
cosx comma space space 0 space less than space straight x space less than straight pi

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240.

Find the local maxima or local minima, if any, of following functions using the first derivative test only. Find also the local maximum and the local minimum values, as the case may be:
sin space 2 straight x comma space space 0 space less than space straight x space less than straight pi


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