Solve by Substitution method .

Question

x+y=3

y=x-1

 

What is the Solution of the system? _________

(Type an ordered pair.)

Answer 1

The second equation gives you a way to express y in terms of x -- y = x - 1.

 

So you can substitute x-1 for y in the first equation.  That would give you an equation with only x, and that can be solved.

 

So...

 

x + y = 3

x + (x-1) = 3

2x - 1 = 3

2x = 4

x = 2

 

And since y = x-1, y must be 1.

 

To express this as an ordered pair (in other words, (x, y)),  you'd just write (2, 1).