7.1 exercises

pg. 459

#9 y=2x-1
2y=x-2

y=2x-1 is a straight line with y intercept of (0,-1), and a slope of 2.

in slope intercept form 2 is the slope.

the graph of 2y=x-2 or y=1/2x-1 is a straight line with y intercept of (0,-1) with the slope of 1/2.

ex. 2 pg. 453

2(y+2) =x
x-2y=4

has many solutions;

solution;
solve the system by graphing;

2(y+2)=x
2y+4=x
put into slope format
subtract 2 from each side and divide y1/x1/y2/y1
y=+2/4 1/2x
y=1/2x-2
2/4=1/2 x-2

x-2y=4
+x-2y=4
-2y=-x+4
then in slope intercept form;

y=2/4 1/2x-2
y=1/2-2

because the equations have the same slope intercept form, the original equations are equilevant. Their graphs are the same straight line. Every point on the line satisfies both equations of the system. Their are infinitely many points in the sokution set. The solution set is (x,y)