Question

How do you solve `x- 4\cos x = 0`?

Answer 1

`x=1.2`, `x=-2` and `x=-3.6`

Explanation:

For these kind of questions, you can either using Newton's method if they give you a starting point or you can solve it by graphing. Both of these methods will only give you an approximation.

For graphing, rearrange the equation so that now it is `x=4cosx` then graph `y=x` and `y=4cosx` on the same graph

graph{(y-x)(y-4cosx)=0 [-10, 10, -5, 5]}

So from your graph, you will notice that the two equations meet at 3 different points. Now all you have to do is to try and give an estimate of the x-value of each of these three points
ie `x=1.2`, `x=-2` and `x=-3.6`