y = 2x + 3
the equation of a line in slope-intercept form is
y = mx + b ( m is the slope and b the y-intercept )
to calculate m use the gradient formula
m = ( y₂ - y₁ ) / (x₂ - x₁ )
with (x₁, y₁) = (- 2, - 1) and (x₂, y₂) = (2, 7)
m =
=
= 2
y = 2x + b ← is the partial equation
to find b substitute either of the 2 points into the partial equation
using (2, 7 ), then
7 = 4 + b ⇒ b = 7 - 4 = 3
y = 2x + 3 ← in slope-intercept form