91Ó°ÊÓ

Equation -$$\begin{gathered} 6x-5y=-75 \\ -x-2y=-13 \end{gathered}$$

Solve a System of Equations by Elimination and find the value of x and y.

Equation -

$$\begin{gathered} 6x-5y=-75 \\ -x-2y=-13 \end{gathered}$$

We can eliminate y's by multiplying the first equation by 2 and second equation by 5 -

$$\begin{gathered} (6x-5y)×2=-75×2 \\ (-x-2y)×5=-13×5 \\ 12x-10y=-150 \\ -5x-10y=-65 \end{gathered}$$

The equation become -

$$\begin{gathered} 12x-10y=-150 \\ -5x-10y=-65 \end{gathered}$$

We Subtractthe x's and y's and constants -

$\begin{array}{l}12x-10y=-150\\ \frac{-5x-10y=-65}{17x=-85}\end{array}$

Solve for x -

$x=-5$

Substitute $\mathit{x}\mathbf{=}\mathbf{-}\mathbf{5}$into the second equation $\mathbf{-}\mathit{x}\mathbf{-}\mathbf{2}\mathit{y}\mathbf{=}\mathbf{-}\mathbf{13}$, Then Solve for y -

$$\begin{gathered} -x-2y=-13 \\ -(-5)-2y=-13 \\ -2y=-13-5 \\ -2y=-18 \\ y=9 \end{gathered}$$

Written as$(x,y)$ will be $(-5,9)$

Check that the ordered pair is a solution to both original equations -

Put $(-5,9)$in the equations -

$$\begin{gathered} 6x-5y=-75 \\ 6×(-5)-5×9=-75 \\ -30-45=-75 \\ -75=-75 \end{gathered}$$

$$\begin{gathered} -x-2y=-13 \\ -(-5)-2×9=-13 \\ 5-18=-13 \\ -13=-13 \end{gathered}$$

The Solution is -$(-5,9)$