[微分] Real Root(s)

[Qmmm (Q蛆蛆)]

                                         4
How many real root(s) does the equation x + 4x+ 1= 0 have ?

(1) at least 1 ;
(2) at least 2 ;
(3) at least 3 ;
(4) at least 4 ;

請問這題該怎麼算呢？謝謝

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