The US Census lists the population of the United States as 249 million in 1990, 281 million in 2000, and 309 million in 2010. Fit a second-degree polynomial P(t)=a_{2}t^{2}+a_{1}t+a_{0} passing through these points, where t represents years after 1990 (so t=0 corresponds to 1990) and P(t) represents population in millions (so P(0)=249). Sketch the parabola, P(t). Use the model to predict the population in the years 2020 and 2030. (Source: US Census Bureau). You may use technology to solve the system of 3 equations and 3 unknowns used to find your coefficients/constants for your model. The setup of your 3x3 linear system must be shown.

US predicted population in 2020 and 2030 will be 333 million and 353 million, respectively.

Step-by-step explanation:

Three different points are required to determine the coefficients of correspondent second-order polynomial. Three linear equations are form after substituting the variables associated with those points. is the year and is the population according to US census, measured in millions. That is to say:

There are different approaches to solve linear equation systems. In this problem, a matrix-based approach will be used and a solver will be applied in order to minimize the effort and time required to make the need operations. The solution of the 3 x 3 linear system is shown as following:

Now, the second-order polynomial is:

, where when .

The predicted populations are:

US predicted population in 2020 and 2030 will be 333 million and 353 million, respectively.

b.an increase in a causes b to decrease

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