Question

Solve the system of equations using substitution.
y = -7x
2x - y = -9

Answer 1

x = -1 , y =7 (-1,7)

Explanation:

`y=-7x\\2x-y = -9\\`

`2x+7x = -9`

`2x+7x = 9x\\`

`9x = -9\\`

`(9x)/(9) =(-9)/(9)`

`x = -1\\`

`y = -7(-1)\\y = 7`

Answer 2

Explanation:

Since y= -7x you will want to substitute the y in the other equation.

2x -(-7x) = -9

2x + 7x = -9

9x = -9

so x will be -1

y= -7(-1)

x= -1

y= 7