To check a solution for a without graphing, we need to substitute the solution into each equation. Then, we have to determine whether all of the equations in the system are true. Let's consider two examples.
Suppose we are given a system and told the solution is
Let's check the given solution by substituting
Since both equations are true,
is a solution to the system.
Consider a second example now.
Suppose we are told
is a solution to the system. Let's see if that's correct!
Since neither equation is true,
is not a correct solution to the system. Note that if only one of the equations produces a false statement, the solution is incorrect.