Question

What is the solution of the system? Use either the substitution method or the elimination method. 7x + 2y = −197x + 2y = −19 −x + 2y = 21

Answer 1

The answer is (−5, 8) i did the quiz and got it right!
hope this helps

Answer 2

The correct option will be the last one: (-5, 8)

Step-by-step explanation

`7x + 2y = -19...................(1) \\\\-x + 2y = 21.........................(2)`

According to substitution method, first we will isolate either
`x` or
`y` from any of the equation. So, we are solving the equation (2) for
`x` now...

`-x+2y=21\\ \\ -x= -2y+21\\ \\ x= 2y-21`

Now we will plug this
`x= 2y-21` into equation (1) in place of
`x`...

`7(2y-21)+2y= -19\\ \\ 14y-147+2y=-19\\ \\ 16y-147=-19\\ \\ 16y=-19+147\\ \\ 16y=128\\ \\ y= (128)/(16)=8`

By plugging
`y=8` into the equation
`x= 2y-21` , we will get...

`x=2(8)-21= 16-21=-5`

So, the solution of the system is (-5, 8)