icalibear
  • icalibear
How to solve systems with elimination? 5x - 2y = 28 -20x + 8y = -100 I know that if there are two of the same variable then they cancel and then it is easy to solve when you add the equations together, but what if neither equation has corresponding variables???
Mathematics
  • Stacey Warren - Expert brainly.com
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katieb
  • katieb
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anonymous
  • anonymous
you have to make them become corresponding 5x-2y= 28 (multiply by 8 ) = 80x-16y =224
icalibear
  • icalibear
How are those corresponding :s
anonymous
  • anonymous
and you have to make this for the second one -20x +8y=-100 (muliply by 2) = -40x +16y = -200 and solve by elimination now

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anonymous
  • anonymous
eliminate 16y
icalibear
  • icalibear
why did you multoply by 8 and 2 sorry
UsukiDoll
  • UsukiDoll
If I was given that problem I would eliminate x... seems easier if I distribute the 4 all over the first equation
UsukiDoll
  • UsukiDoll
and for that reason. I have to distribute the 4 all over the first equation because I want to eliminate a variable and solve for the other. In this case, 4(5x-2y=28) 20x-8y=112 (this is my new first equation) so I add my new first equation to the second equation so I can get rid of the x
anonymous
  • anonymous
to make them corresponding...
anonymous
  • anonymous
@Michele_Laino please help
icalibear
  • icalibear
i got 3/5...
UsukiDoll
  • UsukiDoll
oh geez we are forced to take the y's out and then solve for x because by distributing the 4 all over the first equation, I ended up destroying x and y., and we don't want that.
UsukiDoll
  • UsukiDoll
\[8(5x-2y=28)\] \[2(-20x+8y=-100)\] \[40x-16y=224\] \[-40x+16y=-200\] HUH? Am I reading this wrong? even I got the same problem.
anonymous
  • anonymous
i was right @icalibear
icalibear
  • icalibear
|dw:1434862139806:dw|
icalibear
  • icalibear
i meant to type 40x
icalibear
  • icalibear
sorry! typo
icalibear
  • icalibear
i will fix this
UsukiDoll
  • UsukiDoll
we are supposed to distribute 8 and 2 THROUGHOUT THE equation. We can't have it one sided
icalibear
  • icalibear
|dw:1434862362988:dw|
UsukiDoll
  • UsukiDoll
your x portion is off and when you fix it... x and y will cancel
anonymous
  • anonymous
i made a mistake on the multiplication.. sorry
hartnn
  • hartnn
40x - 40x = 0 -16y +16y = 0 224 -200 =24 so you get 0 = 24 in the end. Is that even possible?
icalibear
  • icalibear
is there even a solution if both x and y cancel because that leaves nothing
UsukiDoll
  • UsukiDoll
it's an inconsistent system which leads to no solutions at all
hartnn
  • hartnn
0 =24 true or false?
icalibear
  • icalibear
false..
icalibear
  • icalibear
so there is no solution
hartnn
  • hartnn
right, so there is NO value of x or y which can satisfy those 2 equations. correct, no solution!
icalibear
  • icalibear
okay
icalibear
  • icalibear
thanks so much guys.. i do not remember this from 9th grade..
UsukiDoll
  • UsukiDoll
yeah. I did it both ways... when I tried to eliminate x and I ended up with x and y going away similarly when I tried to eliminate y, I ended up and x and y going away as well leaving me with both situations having LHS doesn't equal the RHS left hand side doesn't equation the right hand side.
icalibear
  • icalibear
okay
UsukiDoll
  • UsukiDoll
but I still would've done the x first... multiply that first equation by 4 makes it faster to get to the conclusion
UsukiDoll
  • UsukiDoll
\[4(5x-2y=28)\] \[-20x+8y=-100\] \[20x-8y=112\] \[-20x+8y=-100\] adding these two equations forces x and y to disappear.
icalibear
  • icalibear
I have one more..
icalibear
  • icalibear
I multiplied to get the middle terms the same but then i got a fraction
icalibear
  • icalibear
Nevermind made an error ! 6 x 3 is 18
icalibear
  • icalibear
|dw:1434862940828:dw|
icalibear
  • icalibear
is this set up right
hartnn
  • hartnn
yes!
UsukiDoll
  • UsukiDoll
yes it is.
icalibear
  • icalibear
so x = 9
hartnn
  • hartnn
yup
icalibear
  • icalibear
okay
hartnn
  • hartnn
y =.. ?
UsukiDoll
  • UsukiDoll
yay... that was fast x)
hartnn
  • hartnn
yes, she got it, she is now unstoppable! ;)
UsukiDoll
  • UsukiDoll
:D
icalibear
  • icalibear
I didnt need to find y for the question but i know you would substitute it back in
icalibear
  • icalibear
thanks so much guys :)
hartnn
  • hartnn
right, go ahead and find it...you're doing it to learn, right? not just for completing the homework...
icalibear
  • icalibear
yes this is just practice
UsukiDoll
  • UsukiDoll
practice is fine....it's the questions with so many questions and multiple choices with omg this is due in an hour are frown upon on os
icalibear
  • icalibear
this isnt a class i get credit for, its just summer prep so i can get into math 128 in the fall
icalibear
  • icalibear
ive graduated and I forgot every bit of this intermediate algebra!
UsukiDoll
  • UsukiDoll
actually... well in my textbook... this is elementary algebra 1
icalibear
  • icalibear
either way, I need a refresher
hartnn
  • hartnn
waiting for the y value :P
icalibear
  • icalibear
sorry i have moved way on.. D:
hartnn
  • hartnn
its ok ^_^ probably next time :)
icalibear
  • icalibear
Yep

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