SOLUTION: The graph of a function F(x)=mx + b contains the points (5,15) and (-3,-5). Find b.

The graph of a function F(x)=mx + b contains the points (5,15) and (-3,-5). Find b.



Formula for slope (m)



         

     m = __________

         



(,) = (5, 15)



(,) = (-3, -5)



 

            -5 - 15

       m = __________

            -3 - 5



             -20          5

         =  ______ or    ___

             - 8          2



To find the f(x),





        F(x) = mx + b , m = 5/2, (x, y) = (5, 15)



                  15 = (5/2)(5) + b

                  15 = 25/2 + b

           15 - 25/2 = b

         30/2 - 25/2 = b

                 5/2 = b 

          



   F(x) = (5/2)x + 5/2



The graph looks like this