## MeganDarling Group Title Really need help! Been trying to solve for a while. 1. Solve the system by using a table. 3y=4x+7 , -4x-4y=28. These are the possible solutions:(–4, –3),(–3, –4), (4, 3),(3, 4). 2.Solve by graphing. -3x-y=-10, 4x-4y=8. possible solutions:(-1,3), (3-1), (1,3), (3,1) one year ago one year ago

1. MeganDarling Group Title

Also help with this problem : The spreadsheet shows the monthly revenue and expenses for a new business. Use the models to predict the month in which revenue will equal expenses. Possible answers: October September August May

2. MeganDarling Group Title

help with any of them would be really appreciated (:

3. L.T. Group Title

4. MeganDarling Group Title

your estimate is as good as any haha. I have no clue so even an educated guess is better than nothing

5. MeganDarling Group Title

I honestly just suck horribly at solving systems of any sort x.x

6. L.T. Group Title

I answered it that way by reproducing the pattern of increase in the revenue and expense columns--that is, by adding differences in a row. Does that sound legitimate?

7. MeganDarling Group Title

Sounds alright to me haha

8. L.T. Group Title

I think I can solve the system, but I'm not sure what is meant by table. Is it all right if you use substitution and elimination?

9. MeganDarling Group Title

I would just really like some help with the 1st two because there are lot's of other questions like them, including on upcoming tests. That I really don't want to get wrong :/

10. MeganDarling Group Title

Yeah that's what I was trying to do. I however looked up solving solutions on google and it showed a way to do it where you used a graph to figure out where the two lines crossed. It didn't make sense with my equation though.

11. satellite73 Group Title

$-3x-y=-10$$4x-4y=8$ first equation is the same as $$y=-3x+10$$ so you can replace $$y$$ in the second equation by $$-3x+10$$ with judicious use of parentheses you get $4x-4(-3x+10)=8$ and now you have one equation and one variable to solve

12. satellite73 Group Title

you get $4x+12x-40=8$ $16x-40=8$ $16x=48$ $x=48\div 16=3$

13. MeganDarling Group Title

As long as it end up with an x and a y and they are one of the options above I really don't understand why it matters so much how we got it haha. I suppose in some cases it really matters but.. Thanks satellite that makes sense. I'll try writing it out.

14. satellite73 Group Title

hope the steps are claere

15. MeganDarling Group Title

yeah I think so, so what next?

16. satellite73 Group Title

now that you have $$x=3$$ you can replace $$x$$ by 3 in either equation to solve for $$y$$

17. satellite73 Group Title

for example we know $$y=-3x+10$$ and we know $$x=3$$ making $$y=-3\times 3+10=-9+10=1$$

18. MeganDarling Group Title

okay haha, I think I get that too x.x

19. satellite73 Group Title

solving by graphing is too much work, and besides, if the answer is $$(-\frac{1}{7}, \frac{5}{7})$$ for example you will never know it from the graph

20. MeganDarling Group Title

I know I really hate it too :/ Then again I hate all math. But it's what they are making us do so .

21. satellite73 Group Title

yes, sometimes math (especially this kind) is hateful that is why they invented computers for example, here is the answer to the first one http://www.wolframalpha.com/input/?i=+3y%3D4x%2B7+%2C+-4x-4y%3D28

22. MeganDarling Group Title

oh wow that's really cool! Thanks alot.