Increasing Rational Function
1. **State the problem:** We need to show that the curve given by the function $$y=\frac{2x+1}{3x+6}$$ is increasing for all $$x \neq -2$$.
2. **Find the derivative:** To determine where the function is increasing, we find its derivative $$y'$$ with respect to $$x$$.
Using the quotient rule: $$y' = \frac{(2)(3x+6) - (2x+1)(3)}{(3x+6)^2}$$.
3. **Simplify the numerator:**
$$ (2)(3x+6) - (2x+1)(3) = 6x + 12 - (6x + 3) = 6x + 12 - 6x - 3 = 9 $$.
4. **Write the derivative:**
$$ y' = \frac{9}{(3x+6)^2} $$.
5. **Analyze the sign of the derivative:**
The denominator $$ (3x+6)^2 $$ is always positive except at $$ x = -2 $$ where it is zero (and the function is undefined).
Since the numerator is positive (9), the derivative $$ y' $$ is positive for all $$ x \neq -2 $$.
6. **Conclusion:**
Because $$ y' > 0 $$ for all $$ x \neq -2 $$, the function $$ y=\frac{2x+1}{3x+6} $$ is increasing on its entire domain except at $$ x = -2 $$ where it is undefined.