Search
Ask a question
0

find the slope intercept form of the equation of the line through the points (-4,2) and (0,-5)

Js there a formula? is it y2-y1 divided by x2-x1??

2 Answers by Expert Tutors

Tutors, sign in to answer this question.
Parviz F. | Mathematics professor at Community CollegesMathematics professor at Community Colle...
4.8 4.8 (4 lesson ratings) (4)
0
a)
 
Y = mx +b
   
   m = slope       ( Y2 - Y1) / (X2 - X1)= ( 2- (-5) ) / ( -4 -0) = -7/4
 
    Y = -7/4 x + b
 
    The coordinates of points should work:
 
       -5 = 0(X) + b
      
        b =- 5
 
    Y = -7/4 x- 5      ./equation of the line.
 
  b)
 
   7X + 4y =-20     ? in standard form
Kevin F. | Computer Programming and Mathematics TutorComputer Programming and Mathematics Tut...
5.0 5.0 (3 lesson ratings) (3)
0
Hi Gina,
 
You are close. The formula you listed is the formula to find the slope of the line. By plugging in values from the two points, it becomes:
 
-5 - 2    -7
------ =  --
0 - -4     4
 
So, -7/4 is the slope of the line. Recall that the slope-intercept form is y = mx + b, where m is the slope, and b is the y-intercept. So now that you know the slope, you have:
 
y = -7/4x + b
 
To find b, use either of your two given points and plug the x and y values into your equation. Lets use (-4,2), so x is -4 and y is 2:
y = -7/4x + b
2 = -7/4(-4) + b
2 = 7 + b
-5 = b
 
So the final equation is:
 
y = -7/4x - 5
 
Double check by plugging in values from your second given point, (0, -5):
-5 = -7/4(0) - 5
-5 = -5