The function f(x)=x^3-2x-1 has a root in the interval

Answer 1

f(-1) = (-1)^3 - 2(-1) - 1 = -1 - 2(-1) - 1 = -1 +2 - 1 = 1-1 = 0

-1 | 1 0 -2 -1

-1 1 1

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1 -1 -1 0

x^2 - x - 1 = 0

[1 +or- sqrt ( 1 + 4(1))]./ 2

[ 1 +or- sqrt(5))/2