Casio fx-CG50 field manual for IB Math
Finding roots of a polynomial
Use the calculator's polynomial root finder to enter the coefficients of a polynomial and read all real roots.
Find the real roots of x3−7x+6=0.
From the MAIN MENU, open Equation. If you're already inside another app, press first to get back to MAIN MENU.
Press (POLY), then again for degree 3: the soft keys offer degrees 2 to 6.
Enter the coefficients in descending powers of x: 1, 0, -7, 6. The x2 coefficient is 0, so include that zero. Use for the negative sign in -7 and after each entry.
Press (SOLVE). The Casio lists the real roots.
The roots are x=2, x=1, and x=−3. The calculator lists them in its own order, not smallest first.
Your turn
Work each one on your calculator, then check the answer.
- 1
Find all real roots of x3−13x+12=0.
- 2
Find all real roots of x3−19x+30=0.
- 3
Find all real roots of x3−21x−20=0.