Example 11 - Find intervals in which f(x) is strictly - Find intervals of increasing/decreasing

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  1. Chapter 6 Class 12 Application of Derivatives
  2. Serial order wise
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Example 11 Find the intervals in which the function f given by f =4 3 6 2 72 +30 is (a) strictly increasing (b) strictly decreasing. f =4 3 6 2 72 +30 Step 1: Calculating f (x) f =4 3 6 2 72 +30 =12 2 12 72 =12 2 6 =12 2 2 3 6 ( ) =12( ( 2) 3( 2)) =12 2 3 Step 2: Putting f (x) = 0 12 2 3 =0 2 3 =0 So, x = 2 and x = 3 Step 3: Plotting point on real line The points divide the real line into 3 disjoint intervals. i.e. 2 2 ,3 & 3 , uc1 Step 4: (a) f is strictly increasing in , & , uc1 (b) f is strictly decreasing in ,

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