First step: Evaluate the fuction at two x-values for which there is a change in the sign of f(x), x1 and x2.

Step 2: Bisect i.e take the average of these two x-values xav.

Step3: For greater accuracy, repeat steps 1 and 2 using a number within the range xav.1 and x2.

Keep doing so to how many decimal places required.

If you still have problems with it, send me a message and I'll solve the answer for you.