How to graph a quadratic function

(Annas Bentari_2010110047)

For example f(x) = x² + 3x -4

1.    Based on the function, you should find the intercept of x and y.

2.    The y-intercept is y= f(0)= 0² +3.(0) -4 = -4

3.    Then the x-intercept(s) are found by solving the equation:

x² + 3.(0) - 4 = 0

By using the factorization formula, the x-intercept(s) are:

x² + 3.(0) - 4 = 0

(x+4) (x-1) = 0

x = -4 v  x = 1

So, there are two x-intercepts: x1 = -4 and x2= 1

4.    Find the vertex point by using (h,k):

h = -b/2a = -3/2.(1)= -3/2

k = f (h)= f (-3/2)= (-3/2)² + 3 (-3/2) -4 = -25/4

5.    Then, graph the quadratic functions by plotting the y-intercept point and x-intercept points, also the vertex point at (h, k) or (-3/2, -25/4)

6.    The conclusion: the graph is an upward.