You can
put this solution on YOUR website!Any rational zero can be found through this equation

where p and q are the factors of the last and first coefficients
So let's list the factors of 21 (the last coefficient):
Now let's list the factors of 1 (the first coefficient):
Now let's divide each factor of the last coefficient by each factor of the first coefficient
Now simplify
These are all the distinct rational zeros of the function that could occur
Note: these are all of the
possible roots. To find the actual rational roots (if there are any), you need to plug each possible root into the given polynomial. If you get a result of 0, then the corresponding input is a zero.