How to Use Excel to Solve a Polynomial

1. Input the coefficients into separate cells in row 4 in Excel, starting at cell 'B4.' for example, if you have a cubic equation x^3 - 2x^2 - 3x, then your coefficients are 1, -2, 6 and -3. Click on cell 'B4' and type '1', then click on cell 'C4' and type '-2,' then click on cell 'D4' and type '6,' then click on cell 'E4' and type '-3.'
2. Click on cell 'B6' and type a guess for the value of X. If you have no idea of what the value might be, just type '0.'
3. Click on cell 'G4' and then type the full equation into the cell. In this example, the equation would be 'x^3 - 2x^2 - 3x.'
4. Click on the 'Data' tab, then click on 'What-If Analysis,' in the Data Tools group and then click 'Goal Seek.'
5. Click on the 'Set cell' text box and type 'G4.'
6. Click on the 'To value' text box and then type '0.'
7. Click on the 'By changing cell' text box and then type '$B$6.'
8. Click on 'OK.' Excel will solve the polynomial and return the result in cell B6 (the initial guess box).