Parabola Questions
1. **Problem 1:** Identify the equation that matches the given graph of a downward opening parabola with vertex near $(2,4)$ and x-intercepts near $-1$ and $5.5$.
- Equation options:
A) $y = -x^{2} + 3$
B) $y = -x^{3} + 3$
C) $y = x^{2} - 3$
D) $y = x^{3} - 3$
- Since the graph is parabolic (quadratic) and opens downward, its equation is a quadratic with a negative leading coefficient.
- Option A matches a downward parabola.
- Checking vertex: vertex of $y=-x^{2}+3$ is at $(0,3)$, which is close but given graph vertex is near $(2,4)$.
- The problem states it is the graph above, so likely equation A.
2. **Problem 2:** Find the parabola with vertex at $(1, 0)$.
- Vertex form is $f(x) = a(x-h)^2 + k$, where vertex is $(h,k)$.
- Check options:
A) $x^{2} + 1$ has vertex $(0,1)$
B) $(x-1)^2$ has vertex $(1,0)$
C) $(x+1)^2$ has vertex $(-1,0)$
D) $x^{2} - 1$ has vertex $(0,-1)$
- Correct choice is B.
3. **Problem 3:** Vertex of $y = (x - 3)^2 + 6$.
- Vertex form is $y=(x - h)^2 + k$, so vertex is $(3,6)$.
- Correct answer B.
4. **Problem 4:** Vertex of $y = 3(x + 2)^2 + 5$.
- Vertex form: $y = a(x - h)^2 + k$, vertex $(h,k)$.
- Here $h = -2$, $k=5$.
- Correct D.
5. **Problem 5:** Vertex of $f(x) = x^2 - 10x + 28$.
- Use $h = -b/(2a) = -(-10)/2 = 5$.
- Calculate $k = f(5) = 25 - 50 + 28 = 3$.
- Vertex $(5,3)$.
- Correct B.
6. **Problem 6:** Vertex of $f(x) = 5x^2 + 20x + 17$.
- $h = -b/(2a) = -20/(2*5) = -2$.
- $k = f(-2) = 5(4) + 20(-2) + 17 = 20 - 40 + 17 = -3$.
- Vertex $(-2,-3)$.
- Correct A.
7. **Problem 7:** Given graph of $y=f(x)$ peaks near $y=5$ at $x=2$ and crosses $y=0$ near $x=5$.
- Find $f(f(2))$.
- Since $f(2) ext{ (peak) } o 5$ (from graph).
- Then $f(5) = 0$ (graph crosses y=0 at x=5).
- So $f(f(2)) = f(5) = 0$.
- Answer A.
8. **Problem 8:** Which equation matches the graph from problem 7?
- Since peak at $(2,4)$ and opens downward, use vertex form: $y = a(x - 2)^2 + 4$ with $a<0$.
- Option B: $y=4 - 0.25(x - 2)^2$ fits vertex at (2,4), downward opening.
- Correct B.
9. **Problem 9:** Square ABCD with area 36 and $h(x) = kx^2$, where A and B on x-axis, C and D on curve.
- Side length $s = ext{sqrt}(36) = 6$.
- Points A and B on x-axis at distance 6, so base length $=6$.
- Height (vertical) is $h = kx^2$, so height = $6$.
- If C and D are at $x=3$ (midpoint), then height $= k imes 3^2 = 9k$.
- Since side = 6, $9k=6 o k=6/9=2/3$.
- Answer E.
10. **Problem 10:** Parabola passes $(3,4)$, vertex $(5,-2)$.
- For parabola with vertex $(h,k)$, symmetric points satisfy $f(5 + d) = f(5 - d)$.
- Distance from 3 to 5 is 2, so point symmetric to $(3,4)$ is $(7,4)$.
- So $(7,4)$ must be on graph.
- Correct D.
11. **Problem 11:** Parabola through $(0,0)$ and $(6,0)$ with turning point $T(h,4)$.
- Vertex $h$ is midpoint of roots: $h = (0 + 6)/2 = 3$, so I is false (h=2 wrong), not I.
- II: Parabola values symmetric around vertex, so if passes $(1,2)$ then passes $(5,2)$.
- True.
- III: If parabola opens downward (vertex max), then vertex is maximum.
- Since $y=4$ at vertex, and roots 0,6, parabola opens downward, so III true.
- Correct answer E (II and III only).
12. **Problem 12:** Quadratic $f(x) = -x^2 - 4x + 1$, axis of symmetry $x=-2$.
- Vertex $(h,k)$ with $h = -b/2a = -(-4)/(2 imes -1) = 4/-2 = -2$, correct.
- Compute $k = f(-2) = -4 + 8 + 1 = 5$.
- Since leading coefficient negative, vertex is maximum point.
- Correct A.
13. **Problem 13:** Parabola has minimum at $(1,-2)$, and $f(5) = f(c)$.
- Parabola symmetric about $x=1$, so $c$ satisfies $|c-1| = |5-1|=4$.
- So $c=1 - 4 = -3$ or $c=5$.
- Correct B.
14. **Problem 14:** Parabola intersects x-axis at $-1$ and $6$, vertex lies midway at $x=(6-1)/2 = 2.5$.
- So vertex x-coordinate is 2.5.
- From options, only C has $x=2.5$.
- Correct C.
15. **Problem 15:** Parabola intersects x-axis at $-2$ and $6$, $f(8) = f(p)$.
- Vertex $x = (6-2)/2 = 2$.
- Distance from 8 to 2 is $6$, so $p$ satisfies $|p-2|=6$.
- Possible $p=2 - 6 = -4$ or $p=8$.
- Given options, $-4$ is option B.
---
Final answers:
1) A
2) B
3) B
4) D
5) B
6) A
7) A
8) B
9) E
10) D
11) E
12) A
13) B
14) C
15) B