h(x) = -3x + 9
h(1) = 6 means y = 6 when x = 1
thus 2 points on the line are (1, 6) and (4, - 3)
the equation of a line in ' slope- intercept form ' is
y = mx + c → ( m is slope and c the y- intercept)
to find m use the ' gradient formula '
m = (y₂ - y₁)/(x₂ - x₁) = ( - 3 - 6)/(4 - 1) = (-9)/3 = - 3
partial equation is y = - 3x + c
to find c substitute either of the 2 points into the equation.
using (1, 6)
6 = - 3 + c ⇒ c = 6 + 3 =9
linear equation is h(x) = - 3x + 9
