Question

How to write (-2,-1) and (2,7) in y=mx+b form

Answer 1

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 = $\frac{7+1}{2+2}$ = $\frac{8}{4}$ = 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