Slope intercept form

Question

write the slope-intercept equatio for the line that passes through (3,-11) and (-7,29).

Answer 1

Say the points

(x1, y1) = (3, - 11)

(x2, y2) = (- 7, 29)

Slope intercept form is y = mx + b.

Line equation is y - y1 = (y2 - y1/x2 - x1)(x - x1).

y + 11 = (29 + 11/- 7 - 3)(x - 3)

y +11 = (40/- 10)(x - 3)

y + 11 = (- 4)(x - 2)

y = - 4x + 8.

Slope intercept form of the line is y = - 4x + 8.

 

Comments

The line equation is y = -4x + 1

Answer 2

The line equation is y = mx + b where m is slope and b is y-intercept

m = (y2 - y1) / (x2 - x1)

= (29 - (-11)) / ( -7 - 3)

= 40 / -10 = -4

Line equatio is y = -4x + b

Find y-intercept by substituing any point on the line say (3, -11)

-11 = -4 * 3 + b

b = 1

 

The line equation is y = -4x + 1