Answer:
The equation of a line in slope-intercept form is y = mx + b, where m is the slope and b is the y-intercept.
In this case, the y-intercept is (0, -1) and the slope is 4. So we have:
y = 4x - 1
Therefore, the equation of the line with y-intercept (0, -1) and slope 4 is y = 4x - 1.