When it "ask for x " you have to give the approximate vale of the solutions. So if you want all four root of this polynomial you have to guess all the root of this polynomial.
How do I find the roots of an nth degree polynomial equation like 5(x^4)-20(x^3)-45(x^2)+34x+23 = 0 using the casio fx-991es? This is a very common calculator being used even in the board exam for engineering in my country..
I can get it to show me all the roots of 1st to third degree equations without a problem by pressing [MODE] then  then it shows me the option of solving a linear, quadratic, and cubic equation; but no option for an nth degree equation. I tried inputting the whole equation, then equating it to 0, then invoking the solve for x function of the calculator by pressing [SHIFT] then [SOLVE]; but it only gives me one root of the polynomial when in fact this polynomial has 3 roots. I know how to solve it with a graphing caclulator or software as well as manually, but I want to know how to make this expensive scientific calculator that claims to have a lot of functions and even is sort of the official calculator for board exams here do it.
edit: I just found something called successive approximations and newton's method, I'm going to check if this works for solving the nth roots..