Question

write the point-slope form of an equation for a line passing through (3,6) with slope m= -1/3

Answer 1

Point slope form is y-y1 = m(x-x1)

Say (x1,y1) = (3,6) and m = -1/3

Line equation is y-6 = -1/3(x-3)

Cross multiplication

3(y-6) = -x+3

3y-18 = -x+3

Add 18 to each side.

3y-18+18 = -x+3+18

3y = -x+21

Divide to each side by 3.

3y/3 = (-x+21)/3

y = (-1/3)x+7

Required line equation is y = (-1/3)x+7

Comments

point - slope - form of an equation for a line passing through (3, 6) with slope (m) = - 1/3 is

y - 6 = (- 1/3)(x - 3).