1: x-intercepts are where there are real solutions.

4: The discriminant is b2 – 4ac, and it is either positive, zero, or negative.

7: Get the square by itself, and then take the square root on each side.

8: This is like the previous problem, except there are two steps (addition and division) needed before taking the square root on each side.

13: You can use the quadratic formula if you set the equation equal to zero first. Make sure that b2 turns out positive, even though b will be negative.

25: A zero is a value that makes the expression equal to zero.

30: Pick two numbers a and c such that (-8)2 – 4ac is greater than zero.

38: An x-intercept represents a real zero.

43: You can substitute 16 – 4y for x in the second equation.

46: The axis of symmetry is xh, where h = -b ÷ 2a.