from tkinter import *

root=Tk()

tex=Text(root, height=23, width=49,bg='black',font='System',fg='white',bd=0)
tex.place(x=3,y=25)
i=1
z=7
n=3
d=4
a=5
for i in range(z):
   text=('A',i+2,'=','(',n,'- 1)','*',d,'+',a)
   tex.insert('2.2',text,)

root.mainloop()

for i in range(z):
       text=('A',i+2,'=','(',n,'- 1)','*',d,'+',a)
       tex.insert('2.2','{}n'.format(text))

#!/usr/bin/env python3
from tkinter import Tk, Text

root = Tk()
text = Text(root, height=23, width=49, bg='black', font='System',fg='white',bd=0)
text.place(x=3, y=25)
n, d, a = 3, 4, 5
for i in range(7):
    text.insert('end', f'A{i+2} = ({n} - 1) * {d} + {a}n')
root.mainloop()

#!/usr/bin/env python3
from tkinter import Tk, Text

root = Tk()
text = Text(root, height=23, width=49, bg='black', font='System',fg='white', bd=0)
text.place(x=3, y=2)

def replace_text(i, n=3, d=4, a=5):
    text.delete("1.0", 'end')
    text.insert("1.0", f'A{i+2} = ({n} - 1) * {d} + {a}')
    if i < 6:
        text.after(500, replace_text, i+1) # replace the next line in .5 seconds

replace_text(0)
root.mainloop()