178k views
1 vote
Write the equation of the line in point-slope form that passes through (5, -1) and has a slope of 2/3

1 Answer

6 votes
Answer: " y = (2/3)x − (13/3) " .
________________________________________________
Note: "point-slope" form; or "slope-intercept form" is:

"y = mx + b" ;

in which "y" is on the left-hand side of the equation, with NO coefficient (except for the "implied coefficient of "1");

m = the slope; and is the coefficient of "x" ;

b = the y-intercept; or the value of "x" at the point which "y = 0" .
____________________________________________________
We are given the following point on the line: (5, -1).

We are given the slope, " m = 2/3 " .

Note the formula:

y − y₁ = m(x − x₁) ; Given "x₁ = 5" ; "y₁ = -1" ; "m = 2/3" ;

Plug in these known values into the formula:
_______________________________________________
y − (-1) = (2/3)*(x − 5) ;

to get:
_______________________________________________
y + 1 = (2/3)x − (2/3)*(5) ;
_______________________________________________
Note: 5* (2/3) = 5/1 * 2/3 = (5*2)/(1*3) = 10/3
_______________________________________________
y + 1 = (2/3)x − 10/3 ;
_______________________________________________
Subtract "1" from EACH side of the equation:
_______________________________________________
y + 1 − 1 = (2/3)x − (10/3) − (1) ; {Note: "3/3 = 1"}.

Rewrite as:
_______________________________________________
y + 1 − 1 = (2/3)x − (10/3) − (3/3) ;

to get:
_______________________________________________
y = (2/3)x − (13/3) .
_______________________________________________
User Marc Witteveen
by
8.3k points

No related questions found