= "§O¹N M· SAU SAI V× SAỎ" "VAR A, B, C
19) = "§o¹n m· sau sai v× saỏ" "var a, b, c:real;" " d:=b*b-4*a*c;" "Writeln('d=',d);" "End." (19, 1) = " a,b, c ph¶i lµ kiÓu integer" (19, 2) = "d cha khai b¸o" (19, 3) = "thiÕu begin" (19, 4) = "thiÕu begin vµ cha khai b¸o biÕn d”*