# 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

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. 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.
------------------------
4 - -5 = 9 yes
4 + -5 = -1, not +1 wrong
2 x = 10
x = 5
then
5+y = 1
y = -4

posted by Damon
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

posted by Damon

## Similar Questions

1. ### algebra homework help

student missed 11 problems on a Chemistry test and received a grade of 65%. If all the problems were of equal value, how many problems were on the test? Round off your answer to the nearest integer. X= # of problems 11= # of
2. ### algebra

A student missed 11 problems on a Chemistry test and received a grade of 65%. If all the problems were of equal value, how many problems were on the test? Round off your answer to the nearest integer. X= # of problems 11= 3 of
3. ### algebra homework help

A student missed 8 problems on a Chemistry test and received a grade of 47%. If all the problems were of equal value, how many problems were on the test? Round off your answer to the nearest integer. My answer is 15 question were
4. ### 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?
5. ### algebra homework help

A student missed 3 problems on a Physics test and received a grade of 94%. If all the problems were of equal value, how many problems were on the test? Round off your answer to the nearest integer. my answer is 5 questions
6. ### precalculus

My book tells me to solve each exponential equation. I am given a lot of problems such as 6^x+1 = 4^2x-1 where I use In in the problem to help get my answer. However, in the same section, the book starts giving me problems such as
7. ### Math

What is the best way to study for a math test? Also, what is the best/most efficient way to write a math test? The format of my tests is usually basic questions, and then word problems. I'm always pressed for time at the end, so I
8. ### Algergra

I am stumped! I have been working on these problems for the longest time and I can not figure out what I am doing wrong. Some how when I get to the last two steps I mess up, and I am beyond frustrated. The directions say: Write an
9. ### math

matthew got 36 problems right out of a total of 40 problems on a test. What percent of the problems did he get right?
10. ### math

there's a question that I don't understand and the direction says that 'solve problems as combination integer problems.remember to rewrite all double sign problems as combination problems before solving' and here's a question 50-

More Similar Questions