Question

Terri graphed a system of linear inequalities. Which ordered pairs are a part of the solution set for this system of linear inequalities? Select two that apply.

(-1, 5)
(2, -4)
(7, -1)
(4, 6)
(5, 2)

Answer 1

Answer: (2, -4) and (7, -1)

Explanation:

Ok, the solutions of the system of inequalities are all the points that lie on the blue shaded part of the graph or in the solid line.

So, in order to see if the points are solutions of the system, then you need to locate the point in the graph and see if it is inside the shaded region or in the solid line (only in the segment that "touches" the shaded region).

Now, we want to find the equation of the solid line, we can see that it passes through the points (0, 6) and (6, 0)

A linear relationship can be written as:

y = a*x + b

where a is the slope and b is the y-axis intercept.

For a line that passes through the points (x1, y1) and (x2, y2), the slope can be written as:

a = (y2 - y1)/(x2 - x1).

Then, in this case, the slope is:

a = (0 - 6)/(6 - 0) = -1.

And to find the value of b, we have that when x = 0, y = 6.

y = 6 = -1*0 + b

6 = b

The equation is:

y = -1*x + 6

(-1, 5) is not in the blue region nor in the solid line, so this is not a solution.

(7, - 1) this point is near the solid line, let's test it:

y(7) = -1*7 + 6 = -1

So the point (7, -1) is on the solid line, and is the other solution of the system.