中等MATH-FUNC-002
What is the axis of symmetry of y = x^2 − 6x + 5?
A. x = −3
B. x = 3✓ 答案
C. x = 6
D. y = 3
解說
The axis is x = −b/(2a) = 6/2 = 3. The line x = −3 reverses the sign. The line x = 6 uses −b/a and forgets the 2. The axis is vertical, so it is not y = 3.