Verified answer

CLS
INPUT  a
INPUT b
INPUT  c
IF b <= c AND b <= a THEN w = b: b = a: a = w
IF c <= a AND c <= b THEN w = c: c = a: a = w
IF c <= b THEN w = c: c = b: b = w
PRINT a; b; c
END

CLS
a:
INPUT "введи a"; a
IF a = 0 THEN PRINT "уравнение не квадратное": SLEEP 1: GOTO a
INPUT "введи b"; b
INPUT "введи c"; c
D = b ^ 2 - 4 * a * c
IF D < 0 THEN PRINT "нет решений": END
x1 = (-b + SQR(D)) / (2 * a)
x2 = (-b - SQR(D)) / (2 * a)
PRINT "x1="; x1
PRINT "x2="; x2