What is the difference a ratio and a equation

What is the length of an with endpoints a 3,2 and b 8,14

The customer price index(cpi), which measures the cost of a typical package of customer goods, was 208.8 in 2011 and 244.1 in 2016.let x=11 corresponding to the year 2011 an estimate to cpi into 2013 and 2014. assume that the data can be modeled by a straight line and the trend to continue idenfinitely. use data points to find such a line and then estimate the requested quantities

In which direction does the left side of the graph of this function point? f(x) = 3x3 - x2 + 4x - 2