Question

Find the missing coordinate if the ordered pair is to be a solution to the equation 3x+y=9:(?,-9)

Answer 1

3x + (-9) = 9
3x - 9 = 9
3x = 9 + 9
3x = 18
x = 18/3
x = 6 ← missing coordinate

Answer: (6, -9)

Answer 2

The ordered pair (6, -9) is a solution to the equation
`3x+y=9`

Explanation:

A point is said to lie on the graph, if the point can satisfy that equation of the line. To check if a particular point satisfies an equation, all you have to do is substitute the value of the point in that equation and check if it validates the equation.

We know the equation of the line
`3x+y=9` and the ordered pair (a, -9) is a solution to the equation.

Substitute this point into the equation

`3a+(-9)=9`

and solve for a

`3a-9=9\\3a-9+9=9+9\\3a=18\\(3a)/(3)=(18)/(3)\\a=6`

The ordered pair (6, -9) is a solution to the equation
`3x+y=9` because when you substitute the value of the point into the equation it validates the equation.

`3(6)+-9=9\\18-9=9\\9=9`