Verified answer

from tkinter import *

import tkinter.messagebox as msb

def btn1_func():

   global root

   root.geometry("700x700")

   root.configure(bg = "gray")

   root.title("Задача 3.2")

   msb.showinfo("Info window...", "Задача 3.2")

def btn3_func():

   global root

   root.geometry("500x500")

   root.configure(bg = "pink")

   root.title("Задача 3.1")

   msb.showinfo("Info window...", "Задача 3.1")

root = Tk()

root.title("Window title...")

root.geometry("1000x600")

root.configure(bg="lightgreen")

btn1 = Button(master=root, text="Button-1", command = btn1_func)

btn3 = Button(master=root, text="Button-3", command = btn3_func)

btn1.pack()

btn3.pack()

root.mainloop()