1. **State the problem:**
Find the difference quotient $$\frac{f(x+h)-f(x)}{h}$$ for the function $$f(x) = x^2 - 3x$$.
2. **Write the formula for the difference quotient:**
$$\frac{f(x+h)-f(x)}{h}$$
3. **Calculate $$f(x+h)$$:**
$$f(x+h) = (x+h)^2 - 3(x+h)$$
Expand the square and distribute:
$$= x^2 + 2xh + h^2 - 3x - 3h$$
4. **Calculate $$f(x+h) - f(x)$$:**
$$= (x^2 + 2xh + h^2 - 3x - 3h) - (x^2 - 3x)$$
Simplify by canceling terms:
$$= \cancel{x^2} + 2xh + h^2 - 3x - 3h - \cancel{x^2} + 3x$$
$$= 2xh + h^2 - 3h$$
5. **Form the difference quotient:**
$$\frac{f(x+h)-f(x)}{h} = \frac{2xh + h^2 - 3h}{h}$$
6. **Simplify by factoring out $$h$$ in the numerator:**
$$= \frac{h(2x + h - 3)}{h}$$
Cancel $$h$$:
$$= \cancel{\frac{h}{h}}(2x + h - 3)$$
$$= 2x + h - 3$$
**Final answer:**
$$\frac{f(x+h)-f(x)}{h} = 2x + h - 3$$
This expression represents the average rate of change of the function $$f$$ over the interval from $$x$$ to $$x+h$$.
Difference Quotient 85302C
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