### The second order equation: Ax^{2} + Bx + C - back to content

**
?- start.
Input the coefficients:
A= 1.
B= -3.
C= 2.
Solutions are x1= 2 x2= 1
Do you want to continue(y/n)? n.
**

start:- reads(A,B,C),solve(A,B,C),!,continue.
reads(A,B,C):- write('Input the coefficients:'),nl,
write('A='),read(A),write('B='),read(B),write('C='),read(C).
delta(A,B,C,R):- D is (B*B-4*A*C),D >= 0,R is sqrt(D).
solve(A,B,C):- A=\=0,delta(A,B,C,R),
X1 is (-B+R)/(2*A), X2 is (-B-R)/(2*A),
write('Solutions are '),
write('x1= '),write(X1),write(' x2='),write(X2),nl.
solve(A,B,C):- A=0,X is (-C/B),
write('Equation is order I. Solution is: '),write(X),nl.
solve(A,B,C):- delta(A,B,C,R),R=0,X is (-B/(2*A)),
write('Has one solution: '),write(X),nl.
solve(A,B,C):- write('No solutions.'),nl.
continue:- write('Do you want to continue(y/n)? '),
read(X),(X=y;X=ya;X=yes),start.