plzzz ans this is it right or wrong????????????????//

Asked by  | 17th Mar, 2010, 11:26: PM

Expert Answer:

so f'(x)=0 implies



 either both factors must be +ve or both - ve.

if both are negative then





x<1 and x<2   ie common  is  x<1

if both factors are positive, then,

x-1>0 and x-2>0

i.e. the common is x>2

so we see that function is increasing either if x<1 or if x>2

so  if func is increasing then x belongs to open interval minus infinity to 1 union 2 to infinity.


f is decreasing when f'(x)<0

so the product(x-1)(x-2) must be negative

so either

x-1 >0 and (x-2)<0


x-1<0 and x-2>0

continuing like in the first case we get

func is decreasing when 1


Answered by  | 21st Mar, 2010, 04:53: PM

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