If for x = -1 we find the same value of y in both equations, then x = -1 will be a part of the solution of the system.
Let's suppose that x = -1 is the x-coordinate of the solution of the given system
x + y = 4
x - y = 6.
x + y = 4
-1 + y = 4
-1 + 1 + y = 4 + 1
y = 5
x - y = 6
-1 - y = 6
-1 - 6 + y - y = 6 - 6 + y
-7 = y
Since we have two different values for y, we say that x = -1 is not a part of the solution for the given system.
x+xy=8 xy=-x+8 y=-1+8/x
The solution is (x, y, z) = (2.5, 1, 2.5).
solution: y = 0 x = -1
Not sure what you mean; that equation certainly has a solution.
xy + x + y + 1 is an expression, not an equation. An expression cannot be solved.
It equals y+1
x+xy=8 xy=-x+8 y=-1+8/x
The solution is: x = 1 and y = -1
xy + x + y + 1 = (x + 1)(y + 1).
That is the commutative property of equality.
xy = x ÷x y = 1
No.
In the equations Y=X-1 and Y=-X+1, the solution is (1,0)
It is (-1, 3).
1 solution
The solution is (x, y, z) = (2.5, 1, 2.5).
solution: y = 0 x = -1