00:02
In this problem, we're given a system of equations on the board and we're asked to solve it graphically and then confirm our answers by substitution using a calculator.
00:10
To save time, i already plotted the graph.
00:13
You can see it right here on the board.
00:17
Recall, in order to solve a system of equations graphically, we look for what are points that are on both graphs, and it's easiest to find these points by looking at where the two graphs intersect each other.
00:30
I also color coded the graphs.
00:32
So you can see that the red circle is the graph for x squared plus y square is equal to 4, and the blue line is the graph for x minus 2y is equal to 2.
00:42
Looking at the intersections, we see that the two graphs intersect at two points right here, 20 and negative 1 .2, negative 1 .6.
00:52
So our answers are, let's write here, 2 .0 and negative 1 .2, negative 1 .6.
01:06
So we've already solved this system of equations graphically.
01:11
Now is our job to confirm by substitution.
01:15
So let's first check the solution to 0.
01:19
So we plug in 2 for x and 0 for y to see if the equations hold.
01:24
So our first equation becomes 2 squared plus 0 squared plus 0...