Resposta
Use the tilde `~` operator instead of `=` (e.g., $y_1 \sim a x_1^2 + b x_1 + c$). Desmos automatically computes and displays the values of $a$, $b$, and $c$ along with $R^2$.
Explicação
This shortcut is especially powerful for problems with several given data points or graphs where you need to deduce an exact polynomial or exponential model.