Question

Which of the following graphs best represents the solution to the pair of equations below? y = −x + 6 y = 2x − 3 A coordinate plane is shown with two lines graphed. One line passes through the y axis at 6 and through the x axis at 6. The other line passes through the y axis at negative 3 and the x axis at 1.5. The lines intersect at the point 3 comma 3. A coordinate plane is shown with two lines graphed. One line passes through the y axis at 6 and the x axis at 6. The other line passes through the y axis at 3 and the x axis at negative 1.5. The lines intersect at 1 comma 5. A coordinate plane is shown with two lines graphed. One line passes through the y axis at 6 and the x axis at negative 6. The other line passes through the y axis at negative 3 and the x axis at negative 1.5. The lines intersect at negative 3 and 3. A coordinate plane is shown with two lines graphed. One line passes through the y axis at 6 and the x axis at negative 6. The other line passes through the y axis at 3 and the x axis at 1.5. The lines intersect at negative 1 comma 5.

Answer 1

The lines are 

i)  y=-x+6
ii) y=2x-3

The solution of the system of equations is found by equalizing the 2 equations:

-x+6=2x-3

-2x-x=-6-3

-3x=-9

x=-9/(-3)=3

substitute x=3 in either i) or ii):

i)  y=-3+6=3
ii) y=2(3)-3=6-3=3

(the result is the same, so checking one is enough)

This means that the point (3, 3) is a point which is in both lines, so a solution to the system.

In graphs, this means that the lines intersect at (3, 3) ONLY


Answer: The graph where the lines intersect at (3, 3)