1. Let's solve the first problem from 28.a: $5x + 9 - 4x^2 - 9 = 3.3$ 2. Simplify the equation by combining like terms: $$5x + 9 - 4x^2 - 9 = 3.3 \implies 5x - 4x^2 = 3.3$$ 3. Rearrange the equation to standard quadratic form: $$-4x^2 + 5x - 3.3 = 0$$ 4. Multiply both sides by $-1$ to make the leading coefficient positive: $$4x^2 - 5x + 3.3 = 0$$ 5. Use the quadratic formula $x = \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$ where $a=4$, $b=-5$, and $c=3.3$. 6. Calculate the discriminant: $$\Delta = (-5)^2 - 4 \times 4 \times 3.3 = 25 - 52.8 = -27.8$$ 7. Since the discriminant is negative, there are no real solutions for $x$. Therefore, the equation has no real roots. This completes the solution for the first problem in 28.a. Note: The user asked for problems 28 and 29, but per instructions, only the first problem is solved here.