How do you solve the system of equations by graphing and then classify the system as consistent or inconsistent 2x+y=0 and 5x-y=7?

1 Answer

graph{(2x+y)(5x-y-7)=0 [-10, 10, -5, 5]}
color(red)(x=1 & color(magenta)(y=-2

Explanation:

5x-y=7
y=5x-7

Given that, 2x+y=0

Replacing, y=5x-7 in 2x+y=0

2x+(5x-7)=0

7x-7=0

7x=7

color(red)(x=1

Replacing x=1, in y=5x-7

y=5xx1-7

color(magenta)(y=-2

The values are consistent.

Alternatively ,
Consider y=5x-7 and plot the points on the graph that satisfy the equation, such as (0,-7), (2,3)etc
and for 2x+y=0, you could plot (0,0), (2,-2) etc

You would get two lines in the graph. Mark the point of intersection and that's the solution for the equations.
Here, the lines meet at (1,-2). Therefore the solution is, x=1, y=-2 (which matches the answer above:) )

P.S. to get the points to plot on the graph for both the equations, replace x as any value and then get the corresponding value of y from the equality.

~Hope this helps!