Question

Using the completing-the-square method, rewrite f(x) = x2 + 4x − 1 in vertex form.

f(x) = (x + 2)2 + 1
f(x) = (x + 2)2
f(x) = (x + 2)2 + 4
f(x) = (x + 2)2 − 5

Answer 1

f(x) = x² + 4x - 1
f(x) = x² + 4x + 4 - 4 - 1
f(x) = (x + 2)² - 5