Answer:
Happy new year to you and your family and 
 
        
                    
             
        
        
        
The answer is probably the first or second one. I made it easier for you
        
             
        
        
        
If

then the derivative is

Critical points occur where  . This happens for
. This happens for



In the first case, we find

In the second,

So all the critical points occur at multiples of  , or
, or  . (This includes all the even multiples of
. (This includes all the even multiples of  .)
.)
 
        
             
        
        
        
Given :
C, D, and E  are col-linear, CE = 15.8 centimetres, and DE=  3.5 centimetres.
To Find :
Two possible lengths for CD.
Solution :
Their are two cases :
1)
When D is in between C and E .
 .                   .           .
C                  D          E
Here, CD = CE - DE 
CD = 15.8 - 3.5 cm
CD = 12.3 cm
2)
When E is in between D and C.
 .       .                .
D      E              C
Here, CD = CE + DE
CD = 15.8 + 3.5 cm
CD = 19.3 cm
Hence, this is the required solution.
 
        
             
        
        
        
2. 12x5y
 3.7.402 x 10^6
4. 2.36 x 10^2, 2.36 x 10^3, 23.6 x 10^3