Question

Match each graph to the equation of its line.

Answer 1

The upper graph is y=-2x-4
The lower graph is y=-x+2

Use the y=mx+b formula to solve for linear equations.

Answer 2

Answer with explanation:

If the graph passes through two points (a,b) and (c,d) then the equation of line is:

         $y-b=\dfrac{d-b}{c-a}\times (x-a)$

1)

If the graph passes through (1,0) and (0,-4)

Then the equation of line is:

       $y-0=\dfrac{-4-0}{0-1}\times (x-1)\\\\\\y=\dfrac{-4}{-1}\times (x-1)\\\\\\i.e.\\\\\\y=4(x-1)\\\\\\y=4x-4$

2)

If the graph passes through (-2,0) and (0,2)

The equation of line is:

        $y-0=\dfrac{2-0}{0-(-2)}\times (x-(-2))\\\\\\i.e.\\\\\\\\y=\dfrac{2}{2}\times (x+2)\\\\\\i.e.\\\\\\y=x+2$

3)

If the graph passes through (-2,0) and (0,-4)

The equation of line is:

           $y-0=\dfrac{-4-0}{0-(-2)}\times (x-(-2))\\\\i.e.\\\\y=\dfrac{-4}{2}\times (x+2)\\\\\\i.e.\\\\\\y=-2(x+2)\\\\\\i.e.\\\\\\y=-2x-4$

4)

If the graph passes through (2,0) and (0,2)

The equation of line is:

$y-0=\dfrac{2-0}{0-2}\times (x-2)\\\\\\i.e.\\\\\\y=\dfrac{-2}{2}\times (x-2)\\\\\\i.e.\\\\\\y=-(x-2)\\\\\\i.e.\\\\\\y=-x+2$