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https://prnt.sc/oyfpxu

 Aug 28, 2019
 #1
avatar+106535 
+1

(x + 4) ( x + 2) (2x+ 1) (x  - 2) = 0

 

(x^2 - 4) ( x + 4) (2x + 1)  = 0

 

(x^2 - 4) (2x^2 + 9x + 4)  =  0

 

2x^4 + 9x^3 + 4x^2

                        -8x^2   - 36x   - 16     

__________________________

 

2x^4 + 9x^3 - 4x^2 - 36x -  16   = 0 

 

The error was made in multiplying (x + 4) (2x + 1). The first term is 2x^2, not x^2.

 

cool cool cool 

 Aug 28, 2019

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