[F. 1 Maths] Linear Equations in One Unkonwn (1 question)
There are 18 True-or-False questions in a Mathematics test. 2 marks will be given for each correct answers and 1 mark will be deducted for each wrong answer. If Mimi answers all the questions and gets 24 marks, how many correct answers has she got?
[F. 1 Maths] Linear Equations in One Unkonwn (1 question)
2007-08-09 5:36 am
回答 (3)
2007-08-09 6:03 am
✔ 最佳答案
Let x be the number of correct answer she got,and y be the number of wrong answer she got
eq1 : x+y=18
eq2 : 2x-1y=24
From eq1, x-y=18
x=18+y ------- eq3
Sub eq3 into eq2,
2(18-y)-y=24
36-2y-y=24
36-24=2y+y
3y=12
y=4
Sub y=4 into eq1
x+4=18
x=18-4
x=14
I'm not sure if my answers are correct
Just try !
2007-08-10 2:06 am
Let x be the number of correct answer she got,
and y be the number of wrong answer she got
eq1 : x+y=18
eq2 : 2x-1y=24
From eq1, x-y=18
x=18+y ------- eq3
Sub eq3 into eq2,
2(18-y)-y=24
36-2y-y=24
36-24=2y+y
3y=12
y=4
Sub y=4 into eq1
x+4=18
x=18-4
x=14
Hope can help you
and y be the number of wrong answer she got
eq1 : x+y=18
eq2 : 2x-1y=24
From eq1, x-y=18
x=18+y ------- eq3
Sub eq3 into eq2,
2(18-y)-y=24
36-2y-y=24
36-24=2y+y
3y=12
y=4
Sub y=4 into eq1
x+4=18
x=18-4
x=14
Hope can help you
2007-08-09 6:03 am
Let correct answer be x and wrong answer be y
total marks = 24 = 2x-y -------------(1)
total questions = 18= x+y -----------(2)
Eq(1) + Eq(2): 42 = 3x
x = 14, y = 4
Total correct answer is 14
total marks = 24 = 2x-y -------------(1)
total questions = 18= x+y -----------(2)
Eq(1) + Eq(2): 42 = 3x
x = 14, y = 4
Total correct answer is 14
參考: 自己計
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