The number of users y (in millions) for a certain website between November 2008 and January 2009 can be modeled by the equation $\ y=ax^2+bx+c,$ where x represents the age of the user. Using the ordered pair (15,1), (25,8), and (35,3), create a system of linear equations in three variables for a, b, and c. Do this by substituting each ordered pair into the model, creating an equation in three variables. Solve the resulting system to find the coefficients of the model. Then use the model to predict the number of new users for the website who were 20 years old.

Question

The number of users y (in millions) for a certain website between November 2008 and January 2009 can be modeled by the equation  $\ y=ax^2+bx+c,$ where x represents the age of the user. Using the ordered pair (15,1), (25,8), and (35,3), create a system of linear equations in three variables for a, b, and c. Do this by substituting each ordered pair into the model, creating an equation in three variables. Solve the resulting system to find the coefficients of the model. Then use the model to predict the number of new users for the website who were 20 years old.

thesmartone · Answer

The answer was $\ y=\frac{-3}{50}x^2+\frac{31}{10}x-32$ and $\ 6~million$

thesmartone · Answer

Never mind @M4thM1nd Helped me in my last post. http://openstudy.com/study#/updates/546a8945e4b001ceb2688d5b