introductory algebra

I had these problems on my test and for some reason got them wrong. Here are the problems:

Solve:
x-y=9
x+y=1

The test states that the answer is (5,-4)

I've checked ,y work and used substitution to solve this and still get x=4, y=-5.

The second problem is:
Solve the system of equations by graphing.
a=1/2b+5
a-4b=-2

The answer is (6,2)

Again i got the reverse of this; (2,6).

I have been at these for several hours and want to pull my hair out. Are my answers really wrong or is it the test? HELP!

Thanks

  1. 👍
  2. 👎
  3. 👁
  1. x-y=9
    x+y=1

    The test states that the answer is (5,-4)

    I've checked ,y work and used substitution to solve this and still get x=4, y=-5.
    ------------------------
    Check your answer
    4 - -5 = 9 yes
    4 + -5 = -1, not +1 wrong
    Now adding the two equations
    2 x = 10
    x = 5
    then
    5+y = 1
    y = -4

    1. 👍
    2. 👎
  2. a=1/2b+5
    a-4b=-2

    substitute (1/2) b + 5 for a

    (1/2) b + 5 - 4 b = -2

    b + 10 - 8b = -4

    -7 b = -14
    b = 2
    then
    a = 1 + 5 = 6

    1. 👍
    2. 👎

Respond to this Question

First Name

Your Response

Similar Questions

  1. Math

    A test has 12 problems, and each problem is worth 5 marks. Full marks are given for a correct answer, 2 marks are given if there is no answer, and no marks are given for an incorrect answer. Some scores between 1 and 60, are

  2. Social Studies

    Hi so i'm at connections academy. I was doing the feudal Europe unit test and wanted to ensure my grade is good. I'm asking you guys to check my work. (if you did the test, or are a teacher) i will put MY answers down below,

  3. Math

    If a seed is planted, it has a 70% chance of growing into a healthy plant. If 7 seeds are planted, what is the probability that exactly 1 doesn't grow? Here What I did I thought its premutation but some reason I got that wrong, I

  4. Math

    On the six tests in her social studies course, Jerelyn's score were 92, 78, 86, 92, 95, and 91. Determine the median and the mode of her scores. If Jerelyn took a seventh test and raised the mean of her scores exactly 1 point,

  1. math

    a student answered 86 problems on a test correctly and received 98% how many problems were there on the test if they all had the same amount of points. I crossed multiplied but forgot whats next. Please don't give me the answer I

  2. Math: Trig

    What is Arcsec(-2) equal to and how can you find the correct answer? I got 2pi/3 but it was marked wrong on my test and I'm not sure why it's wrong. Can you please explain this to me? Thanks!

  3. math

    a student earned a grade of 80% on a math test that had 20 problems. How many problems on this test did the student answer correctly?

  4. Math

    Consider the following test scores obtained by a class. Test score 90 80 70 60 50 Frequency 1 4 11 6 2 Find the standard deviation (rounded to the nearest hundredth). -------------------------------- I've posted this question

  1. Algebra 1

    Your math teacher tells you that next week's test is worth 100 points and contains 38 problems. Each problem is worth either 5 points or 2 points. Because you are studying systems of linear equations, your teacher says that for

  2. English

    the best reason for milo to rescue rhyme and reason is so that A. milo will pass this test and become a hero. B.the demons will be defeated once and for all C.Azaz and the mathemagician will be happy D.the princesses will restore

  3. Mathematics

    Maria answered all the problems on her math test. She answered 80 percent of the problems correctly. If she answered 6 problems incorrectly, how many problems were on the test?

  4. math

    A test in Science is scored the following way: each correct answer earns 10 points while each wrong answer earns one point less. In a 30-item test, Rafael got 23 correct answers and 7 wrong answers. What was his score?

You can view more similar questions or ask a new question.