How do you write the equation of a line in point slope form and slope intercept form given Point: (1, –7); Slope: -2/3?

1 Answer
May 2, 2015

Point-slope form is #y+7=-2/3(x-1)# .

y-intercept form is #y=-2/3x+ -19/3# .

Point-slope form.

Slope, #m#, = #-2/3#.

Point=#(1,-7)=x_1# and #y_1#.

Point-slope formula.

#y-y_1=m(x-x_1)# =

Substitute the values for #y_1# and #x_1# and #m#.

#y-(-7)=-2/3(x-1)# =

#y+7=-2/3(x-1)#

y-intercept form.

Slope, #m=-2/3#, #y=-7#, #x=1#.

y-intercept formula.

#y=mx+b# =

Substitute the values for #y#, #x#, and #m#. Solve for slope-intercept, #b#.

#-7=-2/3(1)+b# =

#-7=-2/3+b# =

Flip the equation (optional).

#b-2/3=-7# =

Add 2/3 to both sides.

#b=-7+2/3# =

Make the denominators the same.

#b= -7*3/3+2/3# =

#b=-21/3+2/3# =

#b=-19/3#

Now we can write the equation of the line in slope-intercept form.

#y=-2/3x+ -19/3#