Question

What is the equation for a line that contains the point (0,-3) (4,-1)

Answer 1

by inspection: y = 1/2 x - 3

Answer 2

just picture the two points in your head. Then do change in y (2) over change in x (4) = 1/2. And one of the points is already the y-intercept.

Answer 3

\[y=kx+m\]
\[k = {-1-(-3) \over 4-0} = {1 \over 2} \]
\[-3 = {1 \over 2} \times 0 + m\]
\[m=-3\]
\[y={1 \over 2} x -3\]
Test: \[-1 = { 1 \over 2} \times 4 - 3 \] QED