## anonymous one year ago Solve the system of equations and choose the correct answer from the list of options. 2x + y = −4 y = 3x + 2 negative 6 over five comma negative 8 over 5 negative 8 over 5 comma negative 6 over 5 negative 5 over 6 comma negative 11 over 5 negative 11 over 5 comma negative 6 over 5

1. anonymous

2. welshfella

from the first eqaution y = -2x - 4 so you have 2 expressions in x equal to y so equate these 2 and solve for x

3. triciaal

4. triciaal

|dw:1439053101422:dw|

5. triciaal

|dw:1439053564241:dw|

6. anonymous

i dot get it

7. anonymous

$\left[\begin{matrix}2 & 1 \\ 3 & -1\end{matrix}\right]\left[\begin{matrix}x \\ y\end{matrix}\right]=\left[\begin{matrix}-4 \\ -2\end{matrix}\right]$ $A ^{-1}\left[\begin{matrix}\frac{ 1 }{ 5 } & \frac{ 1 }{ 5 } \\ \frac{ 3 }{ 5 } & -\frac{ 2 }{ 5 }\end{matrix}\right]$$\left[\begin{matrix}\frac{ 1 }{ 5 } & \frac{ 1 }{ 5 } \\ \frac{ 3 }{ 5 } & -\frac{ 2 }{ 5 }\end{matrix}\right]\left[\begin{matrix}-4 \\ -2\end{matrix}\right]=?$

8. anonymous

9. anonymous

so what does that mean

10. anonymous

umm you havent learn matrices yet?

11. anonymous

no

12. anonymous

then nvm, later you will learn the hax

13. anonymous

$2x+y=-4$$y=3x+2$you substitute the second equation of y into the first one

14. anonymous

so it becomes $2x+(3x+2)=-4$

15. anonymous

much easier to solve?