Posted by **jose** on Sunday, May 23, 2010 at 6:18pm.

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

- introductory algebra -
**Damon**, Sunday, May 23, 2010 at 6:22pm
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

- introductory algebra -
**Damon**, Sunday, May 23, 2010 at 6:29pm
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

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