Can someone me figure this out? the explanation gave me no idea on how to do this.

By solving both equations:
(x^4 + 5x^2 -36) = 0              (2x^2 +9x-5)=0
(x^2 -4) ( x^2 +9) = 0              (2x-1) ( x+5) = 0 
 (x-2) (x+2) (x^+9) = 0             (2x-1) (x+5) = 0
So from this w get : 
x = 2 , -2 
x= 1/2 
x = -5 
x= 3i , -3i 
and write them in the cells