Heating costs In colder climates the cost for natural gas to heat homes can vary from one month to the next. The polynomial function
f(x)=-0.1213 x^{4}+3.462 x^{3}-29.22 x^{2}+64.68 x+97.69
models the monthly cost in dollars of heating a typical home. The input $x$ represents the month, where $x=1$ corresponds to January and $x=12$ to December. (Source: Minnegasco.)
(a) Where might the absolute extrema occur for $1 \leq x \leq 12 ?$
$\Rightarrow$ (b) Approximate the absolute extrema and interpret the results.