+0  
 
0
49
1
avatar

-2x2-5x=-50

 
Guest Sep 12, 2017
social bar
Sort: 

1+0 Answers

 #1
avatar+76080 
+2

-2x^2 - 5x = -50       multiply through by -1

 

2x^2  + 5x  = 50      complete the square on x

 

2 [x ^2  +  (5/2)x ]  = 50       divide both sides by 2

 

x^2  +  (5/2)x     = 25         take (1/2)  of (5/2)  = 5/4.....square this = 25/16,  and add to both sides 

 

x^2  + (5/2)x  + 25/16  =   25  +  25/16         factor the left side and simplify the right

 

[ x +  5/4 ] ^2   =   [ 400 + 25]  / 16          take both roots

 

x + 5/4  =  ±√ [ 425]  / 4

 

x + 5/4  =   ±5√17 / 4       subtract 5/4 from both sides

 

x  = ±5√17 / 4  - 5/4  =  [  -5  ± 5√17 ] / 4  

 

 

cool cool cool

 
CPhill  Sep 12, 2017

29 Online Users

avatar
avatar
avatar
avatar
avatar
avatar
We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details