The-number-of-negative-real-roots-of-x-4-4x-1-0-is-

Question Number 5639 by Daily last updated on 23/May/16

The number of negative real roots

of x^{4} - 4 x - 1 = 0 is

Commented by Yozzii last updated on 23/May/16

D e s c a r t e s r u l e o f s i g n s m a y h e l p .

Answered by Rasheed Soomro last updated on 27/May/16

T h e e q u a t i o n h a s n o s i g n v a r i a t i o n

s o i t h a s n o p o s i t i v e r o o t .

R e p l a c e x b y - x

{(- x)}^{4} - 4 (- x) - 1 = 0

\Rightarrow x^{4} + 4 x - 1 = 0

T h i s h a s o n e v a r i a t i o n o f s i g n s

S o t h e g i v e n e q u a t i o n h a s o n e n e g a t i v e

r o o t .