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4x+у=3; 6x-5y=11

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4*x + y = 3
4x+y=34 x + y = 3
6*x - 5*y = 11
6x5y=116 x - 5 y = 11
6*x - 5*y = 11
Detail solution
Given the system of equations
4x+y=34 x + y = 3
6x5y=116 x - 5 y = 11

Let's express from equation 1 x
4x+y=34 x + y = 3
Let's move the summand with the variable y from the left part to the right part performing the sign change
4x=3y4 x = 3 - y
4x=3y4 x = 3 - y
Let's divide both parts of the equation by the multiplier of x
4x4=3y4\frac{4 x}{4} = \frac{3 - y}{4}
x=34y4x = \frac{3}{4} - \frac{y}{4}
Let's try the obtained element x to 2-th equation
6x5y=116 x - 5 y = 11
We get:
5y+6(34y4)=11- 5 y + 6 \left(\frac{3}{4} - \frac{y}{4}\right) = 11
9213y2=11\frac{9}{2} - \frac{13 y}{2} = 11
We move the free summand 9/2 from the left part to the right part performing the sign change
13y2=92+11- \frac{13 y}{2} = - \frac{9}{2} + 11
13y2=132- \frac{13 y}{2} = \frac{13}{2}
Let's divide both parts of the equation by the multiplier of y
(1)132y132=13(132)2\frac{\left(-1\right) \frac{13}{2} y}{- \frac{13}{2}} = \frac{13}{\left(- \frac{13}{2}\right) 2}
y=1y = -1
Because
x=34y4x = \frac{3}{4} - \frac{y}{4}
then
x=3414x = \frac{3}{4} - - \frac{1}{4}
x=1x = 1

The answer:
x=1x = 1
y=1y = -1
Rapid solution
x1=1x_{1} = 1
=
11
=
1

y1=1y_{1} = -1
=
1-1
=
-1
Gaussian elimination
Given the system of equations
4x+y=34 x + y = 3
6x5y=116 x - 5 y = 11

We give the system of equations to the canonical form
4x+y=34 x + y = 3
6x5y=116 x - 5 y = 11
Rewrite the system of linear equations as the matrix form
[4136511]\left[\begin{matrix}4 & 1 & 3\\6 & -5 & 11\end{matrix}\right]
In 1 -th column
[46]\left[\begin{matrix}4\\6\end{matrix}\right]
let’s convert all the elements, except
1 -th element into zero.
- To do this, let’s take 1 -th line
[413]\left[\begin{matrix}4 & 1 & 3\end{matrix}\right]
,
and subtract it from other lines:
From 2 -th line. Let’s subtract it from this line:
[63425+(1)3211332]=[0132132]\left[\begin{matrix}6 - \frac{3 \cdot 4}{2} & -5 + \frac{\left(-1\right) 3}{2} & 11 - \frac{3 \cdot 3}{2}\end{matrix}\right] = \left[\begin{matrix}0 & - \frac{13}{2} & \frac{13}{2}\end{matrix}\right]
you get
[4130132132]\left[\begin{matrix}4 & 1 & 3\\0 & - \frac{13}{2} & \frac{13}{2}\end{matrix}\right]
In 2 -th column
[1132]\left[\begin{matrix}1\\- \frac{13}{2}\end{matrix}\right]
let’s convert all the elements, except
2 -th element into zero.
- To do this, let’s take 2 -th line
[0132132]\left[\begin{matrix}0 & - \frac{13}{2} & \frac{13}{2}\end{matrix}\right]
,
and subtract it from other lines:
From 1 -th line. Let’s subtract it from this line:
[4(2)013113(2)13213]=[404]\left[\begin{matrix}4 - \frac{\left(-2\right) 0}{13} & 1 - - -1 & 3 - \frac{\left(-2\right) 13}{2 \cdot 13}\end{matrix}\right] = \left[\begin{matrix}4 & 0 & 4\end{matrix}\right]
you get
[4040132132]\left[\begin{matrix}4 & 0 & 4\\0 & - \frac{13}{2} & \frac{13}{2}\end{matrix}\right]

It is almost ready, all we have to do is to find variables, solving the elementary equations:
4x14=04 x_{1} - 4 = 0
13x22132=0- \frac{13 x_{2}}{2} - \frac{13}{2} = 0
We get the answer:
x1=1x_{1} = 1
x2=1x_{2} = -1
Cramer's rule
4x+y=34 x + y = 3
6x5y=116 x - 5 y = 11

We give the system of equations to the canonical form
4x+y=34 x + y = 3
6x5y=116 x - 5 y = 11
Rewrite the system of linear equations as the matrix form
[4x1+x26x15x2]=[311]\left[\begin{matrix}4 x_{1} + x_{2}\\6 x_{1} - 5 x_{2}\end{matrix}\right] = \left[\begin{matrix}3\\11\end{matrix}\right]
- this is the system of equations that has the form
A*x = B

Let´s find a solution of this matrix equations using Cramer´s rule:

Since the determinant of the matrix:
A=det([4165])=26A = \operatorname{det}{\left(\left[\begin{matrix}4 & 1\\6 & -5\end{matrix}\right] \right)} = -26
, then
The root xi is obtained by dividing the determinant of the matrix Ai. by the determinant of the matrix A.
( Ai we get it by replacement in the matrix A i-th column with column B )
x1=det([31115])26=1x_{1} = - \frac{\operatorname{det}{\left(\left[\begin{matrix}3 & 1\\11 & -5\end{matrix}\right] \right)}}{26} = 1
x2=det([43611])26=1x_{2} = - \frac{\operatorname{det}{\left(\left[\begin{matrix}4 & 3\\6 & 11\end{matrix}\right] \right)}}{26} = -1
Numerical answer [src]
x1 = 1.0
y1 = -1.0
x1 = 1.0
y1 = -1.0