Question

(Lesson 11.3) Solve by adding or subtracting. (2 points)S-2x + 3y = 95.14x + 3y = -9

Answer 1

`\begin{cases}-2x+3y=9{} \\ 4x+3y=-9{}\end{cases}`

As we can see the y coefficients are the same for both equations, then let's SUBCTRAC both equations

`\begin{gathered} (-2x+3y)-(4x+3y)=9-(-9) \\ \\ -2x+3y-4x-3y=9+9 \\ \\ -6x=18 \\ \\ x=-(18)/(6)=-3 \end{gathered}`

Now we have the value of x we can use any of the equations to find y, I'll use the first one

`\begin{gathered} -2\cdot(-3)+3y=9 \\ \\ 6+3y=9 \\ \\ 3y=9-6 \\ \\ 3y=3 \\ \\ y=1 \end{gathered}`

Therefore the solution is

`(-3,1)`

x = -3 and y = 1