Split the Plus-Minus

After the root is worked, one line holds both answers: x = (-5 ± 1) / 2. The ± is a textbook's way of carrying two equations in one, and the finishing move is to split it: the plus case x = (-5 + 1) / 2 = -2, the minus case x = (-5 - 1) / 2 = -3.

On the board the split is your move, exactly like the zero product split: tap the line and break it into its two cases, then work each one's arithmetic to a plain number.

Keep the two cases apart to the end. Adding first and subtracting later inside one line is where signs get tangled; two short case lines stay honest, and each lands on one of the two answers.