How to solve rational equations on my casio fx 115es calculator?

Suppose you cleaned the denominators and ended up with a quadratic equation aX^2+bX+c=0. ( a =3., b=-5.2, c= 1.8)

Press [MODE] [5:EQN][3:aX^2+bX+c=0]. It takes you to a screen that shows a b c and under each one there is a place where to enter the value. While the place under a is highlighted you do 3 [=]. The number is put under a and the highlight moves to below b. Then [(-)]5.2 [=] takes the value of b and the highlight moves under c. 1.8 [=] enters the value for c.

Now, when the values of the coefficients` a, b,c are all in press [=].

The screen shows X1= and the result is at the bottom. Thus the first root (solution) is X1=1.255396793.

To get the second solution (a`quadratic equation can have up to 2 real solutions) you press [=] a second time. The screen displays on the top line and to the left X2=. On the bottom line, and to the right, it shows 0.4779365403. This is the value of the second solution.

If you press [=] another time you are taken back to the screen where you enter the values of the coefficients a,b, and c. If you give new values to a,b, c you will solve another quadratic equation.



For a cubic equation [MODE][5:EQN] [4: aX^3 + bX^2+cX+d= 0] takes you to the entry screen where you give the values of a, b, c. Now you must enter the value for d, but you do not see where to enter it. Use the [RightArrow] to uncover where you enter the value of d. You type the value and Press [=][=] to get X1, another [=] displays X2, and a third [=] displays X3.



Be careful, if one of the coefficients is negative, as in the exemple above, you use the (-) key and not the [ - ] key.



Suppose you cleaned the denominators and ended up with a quadratic equation aX^2+bX+c=0. ( a =3., b=-5.2, c= 1.8)
Press [MODE] [5:EQN][3:aX^2+bX+c=0]. It takes you to a screen that shows a b c and under each one there is a place where to enter the value. While the place under a is highlighted you do 3 [=]. The number is put under a and the highlight moves to below b. Then [(-)]5.2 [=] takes the value of b and the highlight moves under c. 1.8 [=] enters the value for c.
Now, when the values of the coefficients` a, b,c are all in press [=].
The screen shows X1= and the result is at the bottom. Thus the first root (solution) is X1=1.255396793.
To get the second solution (a`quadratic equation can have up to 2 real solutions) you press [=] a second time. The screen displays on the top line and to the left X2=. On the bottom line, and to the right, it shows 0.4779365403. This is the value of the second solution.
If you press [=] another time you are taken back to the screen where you enter the values of the coefficients a,b, and c. If you give new values to a,b, c you will solve another quadratic equation.

For a cubic equation [MODE][5:EQN] [4: aX^3 + bX^2+cX+d= 0] takes you to the entry screen where you give the values of a, b, c. Now you must enter the value for d, but you do not see where to enter it. Use the [RightArrow] to uncover where you enter the value of d. You type the value and Press [=][=] to get X1, another [=] displays X2, and a third [=] displays X3.

Be careful, if one of the coefficients is negative, as in the exemple above, you use the (-) key and not the [ - ] key.