This is a program that can plot graphs for quadratic functions. It employs a picture box as plot area and three text boxes to obtain the values of the coefficients a, b, c of the quadratic equation from the users. This program is useful for high school students and mathematics teachers.

**The Interface**

**The Codes**

**
**Private Sub cmd_draw_Click()

Dim a, b, c As Integer

Dim w, v As Single

a = Val(txt_a.Text)

b = Val(txt_b.Text)

c = Val(txt_c.Text)

'Using a scale of 0.5 cm to represent i unit to draw the graph

' Need to make some transformation as the coordinates in VB start from top left

For w = 0 To 10 Step 0.001

v = a * (5 - w) ^ 2 - b * (5 - w) + c

pic_graph.PSet (w, 5 - v)

Next w

End Sub

Private Sub Command1_Click()

pic_graph.Cls

txt_a.Text = ""

txt_b.Text = ""

txt_c.Text = ""

End Sub

Private Sub Command2_Click()

End

End Sub