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How Many Complex roots does the polynomial equation have?

3x^5-2x+1=0

 

 

A. 2

 

B. 3

 

C. 4

 

D. 5

 Oct 2, 2018
 #1
avatar+111328 
+1

3x^5  - 2x  + 1    =   0 

 

-1 is a root because   3(-1)^5  - 2(-1) + 1   =  -3 + 2 + 1  = 0

 

Look at the graph here : https://www.desmos.com/calculator/3lxzwfyib2

 

The graph never  intersects the  x axis again...so the remaining roots are complex

 

WolframAlpha shows that the polynomial has 4  remaining complex roots : 

 

https://www.wolframalpha.com/input/?i=3x%5E5%C2%A0+-+2x%C2%A0+%2B+1%C2%A0+%C2%A0+%3D%C2%A0+%C2%A00

 

 

cool cool cool

 Oct 2, 2018

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