William W. answered • 07/19/21

Math and science made easy - learn from a retired engineer

The point-slope intercept form? There's a point-slope form and there's a slope-intercept form. But not all three.

Point-slope:

The generic form of the point-slope form is:

y - y_{1} = m(x - x_{1}) where "m" is the slope and a point is (x_{1}, y_{1}) so this line would be:

y - -1 = -2(x - 1) or y + 1 = -2(x - 1)

Slope-Intercept:

The generic form of the slope-intercept is y = mx + b where "m" is the slope and "b" is the y-intercept. So this line would start with y = -2x + b and then we would plug in the point (1, -1) as values of "x" and "y" so that we can calculate the value of "b":

y = -2x + b

-1 = -2(1) + b

-1 = -2 + b

1 = b

Then we plug in that value of "b" to get y = -2x + 1