Question

An expression is shown below:

f(x) = 5x^2+ 2x - 3
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
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)
(10 points)

Answer 1

a: (-1,0) , (3/5,0)

b:(-0.2,-3.2). It will be a minimum

c: To graph, you would first find the vertex using (-b/2a) and then plug that back into the equation to find the y coordinate of the vertex. Once you have the vertex plotted, you can then find the x-intercepts. This can be found by factoring the equation and finding the zeros. These 3 points you plot are enough to graph the line.

Explanation:

For showing work on part a:

Turn 5x^2+2x-3 into

(5x^2+5x) (-3x-3)

5x(x+1) -3(x+1)

Finally:

(5x-3)(x+1)

The zeros from that are -1 and 3/5