Discussion





To solve a system of linear equations by substitution, you first solve one

of the equations for one of the variables to get an expression for that 

variable in terms of the other.  Then you substitute this expression into the 

second equation giving you a single equation in a single variable that can be

solved by ordinary methods







Solution













Solve the first equation for x:



Add -2y to both sides







Take this expression for x and substitute it into the second equation:







Now solve:















Now that you know the value of y, you can substitute it into either of the

original equations and solve for x











So the solution set for the system is the ordered pair (7,3)









Check Answer











Note that the two lines intersect at the point (7,3)

 

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