Can you help me write an equation in point slope form for the line with a slope of -9 that passes through (-1,-3).

Answer 1

There are three ways to write the equation of a line: slope-intercept form, point-slope form, and standard (general) form.

Slope-intercept form: y = mx + b

Here, m is the slope of the line (Δy / Δx) and b is the y-intercept.

Point-slope form: (y − y₁) = m(x − x₁)

Here, y₁ is the y-coordinate of your chosen point and x₁ is the x-coordinate of your point.

Standard form: Ax + By = C

Here, A, B, and C are integers.

We are interested in point-slope form.

m = -9

(x₁, y₁) = (-1,-3)

Let us plug in this information into the formula.

(y - [-3]) = -9(x - [-1])

(y + 3) = -9(x + 1)