The Slope of a Linear Curve The slope of a line or curve is a measure of how steep it is or how sensitive the y-variable is to a change in the x-variable. Slope=ΔyΔx where Δ is the Greek symbol delta that stands for “change in.” When a variable increases, the change is positive; when a variable decreases, the change is negative. The slope of a curve is positive when the rise (change in y) has the same sign (positive or negative) as the run (change in x). The slope of a curve is negative when the