SOLUTION: I'm struggling to help my 8th grade daughter with her algebra........ this is one.......the solution to which system of equations has a positive y value? 4 choices are listed but

Question 393058: I'm struggling to help my 8th grade daughter with her algebra........
this is one.......the solution to which system of equations has a positive y value? 4 choices are listed but this is the one that's supposed to be correct---
y=3x+3 and 2x+3y=0. I keep coming up with a negative value. Can you help? Thank you!
Found 2 solutions by jim_thompson5910, mananth:
Answer by jim_thompson5910(35256) (Show Source): You can put this solution on YOUR website!
Start with the second equation.

Plug in into the first equation. In other words, replace each with . Notice we've eliminated the variables. So we now have a simple equation with one unknown.

Distribute

Combine like terms on the left side

Subtract 9 from both sides

Combine like terms on the right side

Divide both sides by 11 to isolate x

Reduce

Now that we know that , we can plug this into to find

Start with the first equation.

Substitute for each

Multiply

Add

So the solutions are and

If you need more help, email me at jim_thompson5910@hotmail.com

Also, feel free to check out my tutoring website

Jim
Answer by mananth(16946) (Show Source): You can put this solution on YOUR website!
the solution to which system of equations has a positive y value? 4 choices are listed but this is the one that's supposed to be correct---
y=3x+3 and 2x+3y=0. I keep coming up with a negative value. Can you help? Thank you!
...
y=3x+3
y-3x=3..........................1
2x+3y=0. .......................2
...
multiply (1) by -3
we get -3y+9x=-9
add this to (2)
3y-3y+2x+9x=-9
11x=-9
/11
x= -9/11
..
plug value of x in (1)
y-3*(-9/11)=3
y+(27/11)=3
y = 3-(27/11)
y=(33-27)/11
y=6/11 which is positive
...
m.ananth@hotmail.ca

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