asked 175k views
0 votes
Helppppp

Question 9 (Essay Worth 10 points)
(08.01 HC)
Use the function f(x) to answer the questions:
f(x) = 4x² +8x-5
Part A: What are the x-intercepts of the graph of f(x)? Show your work. (2 points)
Part B: Is the vertex of the graph of f(x) going to be a maximum or a minimum? What are the coordinates of the vertex? Justify your answers and show your work. (3 points)
Part C: What are the steps you would use to graph f(x)? Justify that you can use the answers obtained in Part A and Part B to draw the graph. (5 points)

asked
User Sianami
by
7.2k points

1 Answer

6 votes
Part A:

To find the x-intercepts of the graph of f(x), we need to set f(x) = 0 and solve for x:

4x² + 8x - 5 = 0

We can use the quadratic formula to solve for x:

x = (-b ± sqrt(b² - 4ac)) / 2a

where a = 4, b = 8, and c = -5.

x = (-8 ± sqrt(8² - 4(4)(-5))) / 2(4)

x = (-8 ± sqrt(144)) / 8

x = (-8 ± 12) / 8

x = -1/2 or x = 5/2

Therefore, the x-intercepts of the graph of f(x) are -1/2 and 5/2.

Part B:

The vertex of the graph of f(x) can be found using the formula:

x = -b / 2a

y = f(x)

where a = 4, b = 8, and c = -5.

x = -8 / 2(4)

x = -1

y = f(-1)

y = 4(-1)² + 8(-1) - 5

y = -1

Therefore, the vertex of the graph of f(x) is (-1, -1). Since the coefficient of the x² term is positive, the parabola opens upwards, so the vertex is a minimum.

Part C:

To graph f(x), we can use the information obtained in Part A and Part B. The x-intercepts are -1/2 and 5/2, and the vertex is (-1, -1). We can also find the y-intercept by setting x = 0:

f(0) = 4(0)² + 8(0) - 5

f(0) = -5

Therefore, the y-intercept is (0, -5).

We can also find the axis of symmetry by using the x-coordinate of the vertex:

x = -1

Therefore, the axis of symmetry is x = -1.

To draw the graph, we can plot the x-intercepts, y-intercept, and vertex, and then sketch a smooth curve passing through these points. Since the vertex is a minimum, the curve will open upwards. We can also use the axis of symmetry to help us draw the curve symmetrically.

Therefore, the steps to graph f(x) are:

1. Find the x-intercepts by solving 4x² + 8x - 5 = 0.
2. Find the y-intercept by setting x = 0.
3. Find the vertex by using x = -b / 2a and y = f(x).
4. Find the axis of symmetry by using the x-coordinate of the vertex.
5. Plot the x-intercepts, y-intercept, and vertex.
6. Sketch a smooth curve passing through these points, opening upwards and symmetrically about the axis of symmetry.
answered
User Emmy
by
8.3k points
Welcome to Qamnty — a place to ask, share, and grow together. Join our community and get real answers from real people.