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Maths question: Numerical solution of equations

Please help me...The first part is OK where i have (show), i use the graphical approach to solve the problem, but i am stuck in the second part where i have to find n. In the booklet the answer is n=-2.

Show that the equation x^3-x+4=0 has only one root. Given that the root b is such that n<b<n+1 where n is an integer. Find n.

Reply 1

MC REN

Do a sign test for various values of n, where it changes sign you have the answer

Use your graph?

Please write something so that i can understand....by the way how can i use the graph to find n?????

Reply 4

MC REN

The graph crosses the axis at some point between some integers, these are your n and n+1

Or put integers n, n+1 into the equation and for one pair the value of the function f(x) = x^3 - x + 4 will have different sign values (positive/negative)