anonymous
  • anonymous
What is the value of the x variable in the solution to the following system of equations? 7x - 2y = 21 4x + y = 57
Mathematics
  • Stacey Warren - Expert brainly.com
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SOLVED
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katieb
  • katieb
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anonymous
  • anonymous
ummm is this algebra 2?
anonymous
  • anonymous
algebra 1, 2nd year taking it again
anonymous
  • anonymous
once i find the y , i put it in the the first equation right?

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anonymous
  • anonymous
I think so... i asked somebody if they could come and help since I need to understand this better as well since i sort of forgot haha :)
anonymous
  • anonymous
sorry hold on lemme see if that person will come... ;/
anonymous
  • anonymous
okay thank you (:
anonymous
  • anonymous
Hi @jim_thompson5910 thanks for coming :) I also do not understand this 100% haha :) u got my message then i take it? :)
jim_thompson5910
  • jim_thompson5910
double everything in the second equation to get 8x + 2y = 114
anonymous
  • anonymous
sorry (email)
anonymous
  • anonymous
and hi @apoorvk thanks for coming also!!! i appreciate it :)
apoorvk
  • apoorvk
ohkay, @iheartfood - go on and post what you would have done in this problem, and don't worry if it's right or wrong.. :)
jim_thompson5910
  • jim_thompson5910
Now add the two equations 7x - 2y = 21 8x + 2y = 114 -------------- 15x + 0y = 135 Now solve 15x = 135 for x
anonymous
  • anonymous
well i know you're supposed to solve for one, but i did not know you could do that (what @jim_thompson5910 wrote.... so that is another way you can do it??
anonymous
  • anonymous
is that how you do it?? simplify it into one larger equation??
jim_thompson5910
  • jim_thompson5910
that's one way to do it, there is more than one way
anonymous
  • anonymous
okay, what's another way to do it?? i think i remember that you can solve one equation and then plug it in but i couldn't do it for this one... ;/
jim_thompson5910
  • jim_thompson5910
you isolate one variable in terms of the other then you substitute 4x + y = 57 y = 57 - 4x ------------------ 7x - 2y = 21 7x - 2(57-4x) = 21 Now solve for x
anonymous
  • anonymous
x = 9 for my problem right? (:
anonymous
  • anonymous
oh okay cool :) soooo x=45??
jim_thompson5910
  • jim_thompson5910
you are correct, the answer to the first piece is x = 9
anonymous
  • anonymous
oops my bad nvm lol
jim_thompson5910
  • jim_thompson5910
hmm how did you get x = 45?
jim_thompson5910
  • jim_thompson5910
now that you know that x = 9, use this to find y
anonymous
  • anonymous
sorry by bad... lol it's 9 sorry!!
anonymous
  • anonymous
sooo you plug it in right??
anonymous
  • anonymous
so y=21 ???? and x=9 ???
jim_thompson5910
  • jim_thompson5910
yes, pick any equation dealing with y and plug in x = 9 7x - 2y = 21 7(9) - 2y = 21 Solve for y
jim_thompson5910
  • jim_thompson5910
and yes, y = 21
anonymous
  • anonymous
oh i used the second equation.. haha but it works both ways :) u get the same answer for both right?
jim_thompson5910
  • jim_thompson5910
oh the question was just "What is the value of the x variable in the solution to the following system of equations?" so they just want x Usually, they'll want both x and y
jim_thompson5910
  • jim_thompson5910
yes either equation works
anonymous
  • anonymous
oh okay cool! thanks!! i totally understand it now... :) what a refresher!! And @sommersquid did that help??? And thanks again for coming @jim_thompson5910 :)
anonymous
  • anonymous
yesss, it really did (: i just needed help with the second step but i got it now (: thank you so much everyone
jim_thompson5910
  • jim_thompson5910
yw

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