Problem: If the parabola has its vertex on the -axis, then must be:
Answer Choices:
A. a positive integer
B. a positive or a negative rational number
C. a positive rational number
D. a positive or a negative irrational number
E. a negative irrational number
Solution:
When the vertex is on the -axis, and the roots of are equal since this parabola touches the -axis at only one point. and .