Solve $x^2-5x+3=0$ and give both roots correct to 2 decimal places. (√13 ≈ 3.6056)

$D=25-12=13$, so $x=\frac{5\pm \sqrt{13}}{2}=\frac{5\pm 3.6056}{2}$, giving 4.3028 → 4.30 and 0.6972 → 0.70. Chopping 0.6972 instead of rounding it gives the wrong 0.69; forgetting to divide by $2a=2$ gives 8.61 and 1.39.