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cutie.patootie
Group Title
Check my answer
Solve with matrices.
5x 3y = 18 and 2x + 7y = 1
I got ....
x=31/18
y=3/5
Am I right?
 2 years ago
 2 years ago
cutie.patootie Group Title
Check my answer Solve with matrices. 5x 3y = 18 and 2x + 7y = 1 I got .... x=31/18 y=3/5 Am I right?
 2 years ago
 2 years ago

This Question is Closed

dumbcow Group TitleBest ResponseYou've already chosen the best response.1
no...but remember you can check for yourself, plug in those values
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.0
.... that was my line panlac lol
 2 years ago

panlac01 Group TitleBest ResponseYou've already chosen the best response.1
my bad... I can delete it
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.0
no need to delete :)
 2 years ago

cutie.patootie Group TitleBest ResponseYou've already chosen the best response.0
Oh okay, well I did & it wasn't.. Crud. Well I am confused on part of it, so when I have to do one row of the matrices that is 5 13 18 to get it to 1 0 c1 How do I do that?
 2 years ago

amistre64 Group TitleBest ResponseYou've already chosen the best response.0
is this cramer rule? or row operations?
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
I think row of operations is the way to go.
 2 years ago

cutie.patootie Group TitleBest ResponseYou've already chosen the best response.0
Uhh. I don't know.. But I have to get the row to 1 0 c1, like 5 has to change to 1 and 13 has to change to 0 somehow.
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
yeah you have to divide the whole row by 5 then
 2 years ago

hartnn Group TitleBest ResponseYou've already chosen the best response.0
hey cutie,have u been taught matrix inversion?which makes the solution much simpler.....
 2 years ago

cutie.patootie Group TitleBest ResponseYou've already chosen the best response.0
@RyanL. Well that would give me 1 13/5 18/5. How would I get 13/5 to zero with out changing the 1? @hartnn Maybe, math isn't my strong point to I have no idea the fancy names... Sorry.
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
Well when we row reduce we want every number bellow that 1 to be a zero
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
dw:1344704018436:dw well you need to subtract the second row by the first row but before that you need to multiply the first row by 2
 2 years ago

cutie.patootie Group TitleBest ResponseYou've already chosen the best response.0
Why would you multiply the first row by two?
 2 years ago

cutie.patootie Group TitleBest ResponseYou've already chosen the best response.0
Oh wait, nevermind! I gotcha now!
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
dw:1344704116600:dw
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
dw:1344704166215:dw
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
then divide the second row by 8.20 and then subtract the the first row by the second.
 2 years ago

cutie.patootie Group TitleBest ResponseYou've already chosen the best response.0
so the bottom row would be 0 1 1 ? And would that give you.. 1 2/5 13/5 ?
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
dw:1344704298500:dw I like to make them 1s so if I need to divide to multiply it it's going to be easier to do it later.
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
Well no I see that I want to make the first row second column zero right. I'm talking about this numberdw:1344704459156:dw
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
so I then multiply the second row by\[\frac{3}{5}\]and then add it to the first row
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
dw:1344704521394:dw
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
dw:1344704554208:dw
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
dw:1344704592083:dw
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
multiply the second row by \[\frac{5}{3}\]now to get them back to 1
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
dw:1344704647344:dw
 2 years ago

dumbcow Group TitleBest ResponseYou've already chosen the best response.1
tough to teach row operations online...there are a lot of steps use matrix algebra \[Ax = b\] \[x=A^{1}b\] where A is coefficient matrix and b is right side constants \[\left(\begin{matrix}5 & 3 \\ 2 & 7\end{matrix}\right)\left(\begin{matrix}x \\ y\end{matrix}\right)= \left(\begin{matrix}18 \\ 1\end{matrix}\right)\] \[\left(\begin{matrix}x \\ y\end{matrix}\right)= \left(\begin{matrix}5 & 3 \\ 2 & 7\end{matrix}\right)^{1}\left(\begin{matrix}18 \\ 1\end{matrix}\right)\] det(A) = 5*7  2*3 = 41 \[\left(\begin{matrix}5 & 3 \\ 2 & 7\end{matrix}\right)^{1} = \left(\begin{matrix}7/41 & 3/41\\ 2/41 & 5/41\end{matrix}\right)\] \[\rightarrow \left(\begin{matrix}x \\ y\end{matrix}\right) = \left(\begin{matrix}3 \\ 1\end{matrix}\right)\]
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
Yeah but row operations is essential to everything that you will learn ahead so you need to be able to do them at ease. After a while it takes seconds.
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
And I made a mistake I left out a negative sign heredw:1344704797494:dw
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
Thanks @dumbcow It's always good to show that there is more than one way to solve a problem.
 2 years ago

cutie.patootie Group TitleBest ResponseYou've already chosen the best response.0
Oh, so when you multiply and add and what not, does it not apply to the first number in the row?
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
Well I think you mean when we add the second row to the first. The thing is that the first number is a zero so if you multiply it a zero by a number or divide it by another number it will remain zero so when we add it to the first row we will be adding or subtracting a zero.
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
And when you add or subtract a zero from a number it stays the same.
 2 years ago

cutie.patootie Group TitleBest ResponseYou've already chosen the best response.0
Okay, I gotcha. Thanks for the explanation. :) It really helped!
 2 years ago

RyanL. Group TitleBest ResponseYou've already chosen the best response.1
No problem sorry for the messy work hope you could understand it .
 2 years ago

cutie.patootie Group TitleBest ResponseYou've already chosen the best response.0
I did :)
 2 years ago
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