Answer:
the mistake they made was the wrong offset from point (0,0) into the y direction. the incline of the line was correct.
the correct equation is y = 1/2×x - 2, because this line contains both points (4,0) and (0,-2)
Explanation:
we are looking for a line equation
y = a×x + b
the 2 points give us 2 equations to solve for the 2 variables a and b :
0 = a×4 + b
-2 = a×0 + b
=> b = -2
=> -b = a×4, => a = -b/4 = 2/4 = 1/2
so, the right equation for the line going through both points is
y = 1/2×x - 2
the difference to the original equation is simply the offset from the x- axis in the y direction.
the original equation would be parallel to the correct equation but hit the y-axis at (0,4) instead of (0,-2), and it would hit the x-axis at (-8,0) instead of (4,0)