Question

Given the system of equations, what is the x-coordinate of the solution? (matrix)
y = 3 -1/2 x
3x + 4y = 1

22
-17/2
-11

Answer 1

3x + 4(3-1/2x) = 1  Input Values of Y
3x + 12 - 2x = 1  Expand
(-12)  x + 12 = 1  (-12)

Answer : C (x = -11)

Answer 2

Answer:

-11

Step-by-step explanation:

The given system of equations solved by matrix method is to arrange all coefficients into a matrix, and then making zeros in specific columns and rows, until we get an equation with just one variable.

$\left \{ {{y=3-\frac{1}{2}x } \atop {3x+4y=1}} \right.$

$\left \{ {{\frac{1}{2}x+ y=3} \atop {3x+4y=1}} \right.$

In matrix arrangement:

$\left[\begin{array}{ccc}\frac{1}{2} &1&3\\3&4&1\end{array}\right]$

Multiplying by 4 the first row and then subtracting with the second row, we have:

$\left[\begin{array}{ccc}-1 &0&11\\3&4&1\end{array}\right]$

From the firs row, we find that:

$-x+0y=11\\x=-11$

Therefore, the right answer is -11.