How can you apply the remainder theorom

In remainder theorem, first we set the given factor or the divisor to 0 and solve for the variable. Then we put the value of the vriable that we got on setting the divisor to 0, in the given polynomial and check the result. If the result is 0, then the given divisor is a factor, else it is not. For e. g. Suppose we have to see whether x-1 is a factor of x square - 2x+1 or not. So we set x-1to 0 that is x-1=0 which gives x=1. Now we put 1 for x in x square - 2x+1 that is 1-2+1 = 0, so x-1 is a factor of the given polynomial.