3. Solve the following system of equations by
and check your answer.
a) Graphing
Solve the first equation for y.
Solve the second equation for y.
Graph both equations,
and we see that the solution is (3, -1) or x = 3 and y = -1.
Substitute these numbers into the two equations. When we substitute them into the first equation we get
and it checks.
In the other equation we get
and they both check
Solve one of the equations for one of the unknowns. The simplest
unknown would be the x in the first equation. Solve the first
equation for x
Substitute this in for x in the other equation.
This gives us an equation in only one unknown. Solve this equation.
The simplest way to find x is to substitute this solution into
the equation where we expressed x as a function of y.
We need to get the multiply both sides of our equations by
suitable numbers so that the coefficients of one of the unknowns
match up. Multiply the top equation by 3 and the bottom equation
by -1.
To find x, substitute this solution into either one of the original
equations. The simplest would be the first equation.
