+0  
 
0
67
3
avatar

Let r and s be the roots of 3x^2+4x-12=0. Find r^2 + s^2

 Feb 27, 2022
 #1
avatar+36417 
+1

By Vieta   r + s  =  - 4/3       and r s = -12/3 = - 4

 

(r +s)^2   =    r^2   + s^2    +   2 rs    

                               

  (-4/3)^2      =   ( r^2 + s^2)     + 2 ( -4)                  you can finish, yah?

 Feb 27, 2022
 #2
avatar
0

I still dont know, sorry i just don't

Guest Feb 28, 2022
 #3
avatar+36417 
+1

(-4/3)^2      =   ( r^2 + s^2)     + 2 ( -4)                  you can finish, yah?

 

Just simple algebra from here :

 

  16/9        = ( r2 + s2)    - 8

 

(16/9 )  + 8   =  r2 + s2

ElectricPavlov  Feb 28, 2022

10 Online Users