Unit 11: Quadratic Functions · AI-A.REI.4, AI-A.SSE.3
Algebra I Regents
Notes
Choose a method. If there is no x term, isolate and square-root. If it factors nicely, factor. Otherwise use x = (−b ± √(b² − 4ac))/(2a). The discriminant b² − 4ac tells you how many real roots.
Vocabulary
discriminant: b² − 4ac; determines the number of real solutions of a quadratic.
Practice (no calculator unless marked)
When completing the square for x² − 18x + 77 = 0, which equation is a correct step in this process?
A. (x − 9)² = 4
B. (x − 3)² = 2
C. x = ±13
D. x − 9 = ±9
The zeros of the function f(x) = x(x − 5)(3x + 6) are
A. 0, −5, and 2
B. 0, 5, and −2
C. −5 and 2, only
D. 5 and −2, only
When completing the square for x² − 18x + 77 = 0, which equation is a correct step in this process?
A. (x − 9)² = 4
B. (x − 3)² = 2
C. x = ±13
D. x − 9 = ±9
The zeros of the function f(x) = x(x − 5)(3x + 6) are
A. 0, −5, and 2
B. 0, 5, and −2
C. −5 and 2, only
D. 5 and −2, only
When completing the square for x² − 18x + 77 = 0, which equation is a correct step in this process?
A. (x − 9)² = 4
B. (x − 3)² = 2
C. x = ±13
D. x − 9 = ±9
The zeros of the function f(x) = x(x − 5)(3x + 6) are
A. 0, −5, and 2
B. 0, 5, and −2
C. −5 and 2, only
D. 5 and −2, only
When completing the square for x² − 18x + 77 = 0, which equation is a correct step in this process?
A. (x − 9)² = 4
B. (x − 3)² = 2
C. x = ±13
D. x − 9 = ±9
The zeros of the function f(x) = x(x − 5)(3x + 6) are