Back to Use factoring and completing the square — Problem 4 · Task Set 23

HSF.IF.C.8.a Tutor Intake — Factoring and Completing the Square

This short check helps your tutor understand where to start. Answer each question on your own. If you are not sure, give your best try — every response helps your tutor plan your sessions.

Grade 9·11 problems·~13 min·Common Core Math - HS Functions·standard·hsf-if-c-8a

Work through problems with immediate feedback

Procedures

A student rewrites $f(x) = x^{2} + 4x + 1$ by completing the square and
gets $f(x) = (x + 2)^{2} + 1$ . What error did the student make?

The student added $4$ to form the perfect square but forgot to subtract $4$ , so the constant should be $1 - 4 = -3$

The student should have added $2$ instead of $4$ because the formula requires $(b/2)$ , not $b^{2}$

The student made no error; the vertex form is correct

The student should have subtracted $4$ from $x$ inside the parentheses: $(x - 2)^{2}$