Question

Write the equation of a line that passes through point (2,3) and (0,9).

Answer 1

Slope-intercept form:

y = mx + b        

"m" is the slope, "b" is the y-intercept (the y value when x = 0) or (0,y)

To find "m", you can use the slope formula and plug in the two points:

(2,3) = (x₁ , y₁)

(0,9) = (x₂ , y₂)

$m=\frac{y_{2}-y_{1}}{x_{2}-x_{1}}$

$m=\frac{9-3}{0-2}$

$m=\frac{6}{-2}$

m = -3

y = -3x + b

To find "b", you can plug in one of the points into the equation (however they already gave you the y-intercept (0,9) or 9)

(2,3)

y = -3x + b

3 = -3(2) + b

3 = -6 + b

9 = b

y = -3x + 9