Question

Please help Determine whether y varies directly with x. If so, find the constant of variation k and write the equation.

Answer 1

The linear equation:
y = k x + b
We will use first two values and solve the system of equations:
11 = k * 7 + b   / *(-1)
13 = k * 8 + b
 ---------------------
 -11 = - k * 7 - b
  13 =   k * 8 + b
----------------------
   2 = k       
   13 = 16 + b 
    b = 13 - 16 = -3
   y = 2 x - 3 ( y varies directly with x )

Answer 2

X                y
7    +4   = 11
+                 +
1                 2
=                 =
8                13
+                  +
1                  2
=                  =
9                 15
+                   +
1                   2
=                   =
10               17

hope this will help you answering the question of your exercise right