Is (-2,16) a solution to y=-9x-2 and 7x-4y=8

Question

For each orders pair I have to determine whether the numbers is a soulution to the ordered pair

Answer 1

Is (-2,16) a solution to y=-9x-2 and 7x-4y=8

 

Just plug the (-2, 16) in for x, y in both equations and see if they balance.

If it works for both equations then the point is a solution of the system.

 

y=-9x-2

16 = -9(-2) - 2

16 = 18 -2

16  = 16

This works for the first equation

 

7x-4y=8

7(-2) - 4(16) = -14 - 64 = -80 ≠ 8

Since this does not equal 8 the point does not work for the 2nd equation.

 

No, (-2,16) is not a solution to the system of equations 

Answer 2

Just substitute the x and y values into the equation and see if the result is true.