+0  
 
+1
90
1
avatar+467 

help please

 Dec 8, 2020
 #1
avatar+114221 
+1

4 ( 7 + x) ( 2 - x)   =

 

4 ( 14 -5x - x^2)  =

 

-4x^2  -20x   +  56

 

This is a parabola  that opens downward...it will have a max.....

 

The x value that produces the  max  =    - (-20) / ( 2 *  -4)  =  20 / -8 =  - 5/2

 

And  the max is

 

-4 (-5/2)^2  - 20 (-5/2) + 56  =

 

-4 ( 25/4) +  50 +  56

 

-25 + 106  =

 

81

 

cool cool cool

 Dec 8, 2020

44 Online Users

avatar
avatar