Find the difference quotient of $LaTeX: \displaystyle f(x)=- 5 x^{2} + 2 x - 3$ .

The difference quotient is $LaTeX: \displaystyle \frac{f(x+h)-f(x)}{h}$ . Evaluating $LaTeX: \displaystyle f(x+h)=2 h + 2 x - 5 \left(h + x\right)^{2} - 3$ and expanding gives $LaTeX: \displaystyle f(x+h)=- 5 h^{2} - 10 h x + 2 h - 5 x^{2} + 2 x - 3$ Evaluating the difference quotient gives $LaTeX: \displaystyle \frac{(- 5 h^{2} - 10 h x + 2 h - 5 x^{2} + 2 x - 3)-(- 5 x^{2} + 2 x - 3)}{h}$ Simplifying gives $LaTeX: \displaystyle \frac{- 5 h^{2} - 10 h x + 2 h}{h}=- 5 h - 10 x + 2$