Thread: An Algebra 1 Question

Hello all, thank you for your time.

Solve the system:

-x+3y=-1
x+2y=4

I understand how to do this, but my answer was not correct, the book said the answer was:
(14/5,3/5) but I have no idea how it got that. I must have made an error in my work, but I'm not sure where.

I started with x+2y=4 Subtracting 2y makes x=4-2y

Then you plug that into the other equation and you get

-4-2y+3y= -1
Which simplifies to:
-4+y=-1
Adding 4 to both sides:
y=3
Plugging that into the other one:
x+2x3=4
Which simplifies to:
x+6=4
Subtract six:
x=-2

Which gives an answer of (-2,3) but I know this is not corrrect because it does not work when you plug that into x and y for the original two sets.

Where am I making my error here?

Thank you very much

You made your error on the first step. Given and , you can substitute for x into the second equation: . This gives you , or .

Okay, just to make sure, same kind of problem with the -x thing i messed up

Write the equation of the line that is parallel to line A and passes through Point P

Line A=



Point P= (-1,2)

That would be:
right?
Originally it would be +b (y=mx+b) but since it's -x the + changes to a - correct?
If so, it would be

Add 2



and the answer would be


correct?

Sorry made an error

At the end I wrote


then

so


Forgot the negative on the second one

Write the equation of the line that is parallel to line A and passes through Point P

Line A=



Point P= (-1,2)

A line parallel to A has the form y=-x +b.

Substitute the x and y values of point P for x and y to find b.