These 8 problems will be a quick way to assess if your students can use the quadratic formula effectively in solving quadratic equations. The distractor answers take into account possible mistakes the students make. Most of the mistakes students make when using the quadratic formula are:
They forget that –b means to change the sign of b
They also use their graphing calculator or other scientific calculator to square b in the radical and end up with a negative answer. I usually ask my students to take out their calculators and enter -4 to the second power. If their calculator says -16, they need to use parentheses and enter (-4) to the second power. I explain that the scientific calculators are doing order of operations and so it’s squaring the 4 before multiplying to the negative 1, but that will result in the wrong answer.