![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/step1.JPG\")
Observe the table.
\So, the difference of the x values is 1, and the difference of the y values is 4.
\The difference in y values is frice (four times) the difference of x values.
\Then the equation of the function f (x) = y = 4x.![\"\"](\"http://www.mathskey.com/userfiles/image/steps_images/solution.JPG\")
The solution of the equation is y = 4x.