In order to get the smallest value, you want as big of a negative number x as big of a positive number, so the answer is a super small negative. The way we can do this is by having a = -2, and b = 5.
Plug these values in:
\({({-1 \over 2} + {1\over 5})}* {({1 \over 5} - {-1 \over 2})} \). This yields \(\color{red} -21/100\).