Estimate $$\int_{5}^{11.6} (2-14x) dx$$ using $6$ divisions, with left endpoints, right endpoints and midpoints.

The width of each subinterval is $\Delta x$ = .
Using left endpoints gives $L_{6} =$ .
Using right endpoints gives $R_{6} =$ .
Using midpoints gives $M_{6} =$ .

The exact value of the integral is .