We are trying to find the x that makes x^3 -3x - 1 = 0
We can use "divide and average" to find this
Le/t suppose that the answer of x = 1.85 = 0
So (1.85)^3 -3(1.85) - 1 = -.218
The root must be between 1.85 and 1.9
Average ths [ 1.85 + 1.9] /2 = 1.875
Put this into the function
(1.875)^3 -3(1.875) - 1 = -.033
The root must be between 1.875 and 1.9
Average these = [ 1.875 + 1.9 ] / 2 = 1.8875
Put this value into the function
(1.8875)^3 -3(1.8875) - 1 = .062
The root must be between 1.875 and 1.8875
Average these = [ 1.8875 + 1.875 ] / 2 = 1.88125
Put thiis into the function
(1.88125)^3 -3(1.88125) - 1 = .014
The root must be between 1.875 and 1.88125
Average these = [ 1.88125 + 1.875 ] / 2 = 1.878125
Put this into the function ≈ -.009 (1)
The root must be between 1.878125 and 1.88125
Average these = 1.8796875
Put this into the function = .002
The root must be between 1.878125 and 1.8796875
Average these = 1.87890625
Put this into the function = -.0036 ......This agrees with (1) to 2 decimal places
So....the approximate root is ≈ 1.87
[ Note....the true root is ≈ 1.8794 ]