от -∞ до 3
(-∞;3] график функции: ⬇⬇⬇⬇⬇
*̸̵̵̵̸̴̴̸̴̵̸̸̸̵̵̡͓̫͍̺͇͎̻͍̼̼̦͎͓̝̪͍̼̘̟͇̞͇̞͓͎̻̺͔̺̞̘̺̟̞̞̞͍̓̓͒́̈́̾́̽́͐̾̒̓̒̾̈́̔̽̽͌̔̒͐͌͊͒͑̈́̓͊͛̓̀̕͘͘͘͜͠͠͠*̵̴̵̵̸̵̴̴̵̴̵̸̵̴̸̢̡̡̠͍̝͉̘̦͍͇̠̠̙̠͇͓͖͍̙̼̙̦̦̻̙͓̺̙̘͓̪̻͕͔͇̼̪̘̼̔͆̈́̐͌̔̽̿̓͑͋̓̓͛̈́̓̈́͛͋̒͐̒̿̔̾͋̿̈́͑͌̚̕̚͘̚̕͝͠͠͝͝*̸̵̸̴̴̸̵̸̴̴̴̴̴̸̵̵̴̡̦̻̫̺̘͕̺̠̼͙̘̠̦͕̝͕̼̞̟̺͔̠͖͖͚̼͔͎͉̼̼̻̻̞͖̝͙͓͓̙͍͊͛̐̾̿͆̾́͐̓́͋̈́̒̓̽͊̀͑̓̓́͌̀́̓͆̒͆̽͆̒́͑͒̈́͑̓͒̕̕͜͜͜͜͝͠͝͝*̸̸̸̴̴̵̸̵̵̵̵̵̸̴̴̴̸̸̢̪̼͖̫̝͍͇̼̘͕̘͍̪̦͔̪̪̪̞͍̼͙̼͕͖̪̫̺̠̦͙̝̦͍͚̠̘̦͍̦͖̼͖͉̙͎̾̈́̓̾̿̓͋̽͛̔͊͌̈́̀͋̓̓̒̔̒̿͒͛͊̀͒͋̒͋̔͌͐͌͛̓͘̕̚̕̚͘̕͜͝͝͠͝͝͝͝͝͝*̸̸̴̵̸̸̵̸̴̵̴̸̸̸̸̡̡̟͓̠̙̦̪͔̘̞͖̫͕̦̼͔̻͕͉͓͓͉͓̙̼̙͓̪̼̪̫͍͎͇̻̞͛͋̈́̒̽͛̓̈́̒̀͊̔̒͆͛̓̓̾̔͐̽̒͊̽̐͒́̈́̔͑̓̕̚̚̕͜͜͠͠͝͝͝͝͠͠*̴̵̸̴̴̵̴̸̸̵̸̸̴̵̡̡̡̡̢͔̦̼̼̞͇͎̘͎̻͕̻̠͓̝̫̠͚̝͚͕͎͍͓͕̺͙͉̻̝͔̙͍̟͊̽̀̓̓͌͆́̈́͋͐͑̓̾͑͊͑͆̔̐͌̓̒͌͋̚͘͘̚͘͜͜͝͠͠͝͠͝͝͝͠͝*̸̴̵̴̴̵̴̸̵̴̴̴̴̵̴̴̵̸̡̡̢̪͍͉̫͕̠̞̠̺̟͓͕̦̻͓̞͚̼͉̞͇͓̞̪̙͍͙̺͉͇̦̘͍͎͍͎̪͕̙͇̞̟̘͓͉̼̞̘͆͛̐̔͐͆̈́́̔̔̓͌͐̿͑͆̐͑͊͐͒͋͐̓͑͋͌̿̓̾͊̒͋̈́͊͊̚͘̚̕̕̚͘̕̕͝͠͝͠͠*̵̴̸̴̴̴̸̴̵̴̴̡̢̢̡̺̙͙͇͙̞̼͍͚͓̙̫͇͇̘͎̙͙̝̙͔͙̻͐͑͌͐̓͆̓͌̿̐̽͑̒̈́̾͋̐̽̔͌̈́̀͛͆́͐̕͘͜͜͝͝͝*̸̵̵̸̴̸̴̸̸̵̸̴̸̵̸̢̢̡̼͎͕̼̠̼̙͇͎͚̟̝̦̫͉̟̪̟͉̝̦̘͕̼͔͔͔̙̫͎̫̙͕̝͉̫͍̻͑͒̔̈́̈́̓̐͑̐̾̒̽͌͋̈́͋̀̈́͊͑̓̓͒̓͊̈́͑͑̈́͆̽͊̈́̐̚̚̕̕̕͜͝͝͝͠*̸̵̴̴̸̸̸̸̸̸̸̸̴̵̡̡̡̢͚̘̼̟͙͎͍̘̺͍̼͓̫̦̻͚̝̟͓̻͎͚̟̼͔̫̺͉̫͓͕̞̺̟̓͆̐̈́̿̒̔͒͋͛̽͛̿͑͋̿͌͛͆̽̿͋̿̒̔͑̈́̿̚̚͘͘̚̚͘̕͜͜͝͠͝*̸̵̵̵̸̴̴̸̴̵̸̸̸̵̵̡͓̫͍̺͇͎̻͍̼̼̦͎͓̝̪͍̼̘̟͇̞͇̞͓͎̻̺͔̺̞̘̺̟̞̞̞͍̓̓͒́̈́̾́̽́͐̾̒̓̒̾̈́̔̽̽͌̔̒͐͌͊͒͑̈́̓͊͛̓̀̕͘͘͘͜͠͠͠*̵̴̵̵̸̵̴̴̵̴̵̸̵̴̸̢̡̡̠͍̝͉̘̦͍͇̠̠̙̠͇͓͖͍̙̼̙̦̦̻̙͓̺̙̘͓̪̻͕͔͇̼̪̘̼̔͆̈́̐͌̔̽̿̓͑͋̓̓͛̈́̓̈́͛͋̒͐̒̿̔̾͋̿̈́͑͌̚̕̚͘̚̕͝͠͠͝͝*̸̵̸̴̴̸̵̸̴̴̴̴̴̸̵̵̴̡̦̻̫̺̘͕̺̠̼͙̘̠̦͕̝͕̼̞̟̺͔̠͖͖͚̼͔͎͉̼̼̻̻̞͖̝͙͓͓̙͍͊͛̐̾̿͆̾́͐̓́͋̈́̒̓̽͊̀͑̓̓́͌̀́̓͆̒͆̽͆̒́͑͒̈́͑̓͒̕̕͜͜͜͜͝͠͝͝*̸̸̸̴̴̵̸̵̵̵̵̵̸̴̴̴̸̸̢̪̼͖̫̝͍͇̼̘͕̘͍̪̦͔̪̪̪̞͍̼͙̼͕͖̪̫̺̠̦͙̝̦͍͚̠̘̦͍̦͖̼͖͉̙͎̾̈́̓̾̿̓͋̽͛̔͊͌̈́̀͋̓̓̒̔̒̿͒͛͊̀͒͋̒͋̔͌͐͌͛̓͘̕̚̕̚͘̕͜͝͝͠͝͝͝͝͝͝*̸̸̴̵̸̸̵̸̴̵̴̸̸̸̸̡̡̟͓̠̙̦̪͔̘̞͖̫͕̦̼͔̻͕͉͓͓͉͓̙̼̙͓̪̼̪̫͍͎͇̻̞͛͋̈́̒̽͛̓̈́̒̀͊̔̒͆͛̓̓̾̔͐̽̒͊̽̐͒́̈́̔͑̓̕̚̚̕͜͜͠͠͝͝͝͝͠͠*̴̵̸̴̴̵̴̸̸̵̸̸̴̵̡̡̡̡̢͔̦̼̼̞͇͎̘͎̻͕̻̠͓̝̫̠͚̝͚͕͎͍͓͕̺͙͉̻̝͔̙͍̟͊̽̀̓̓͌͆́̈́͋͐͑̓̾͑͊͑͆̔̐͌̓̒͌͋̚͘͘̚͘͜͜͝͠͠͝͠͝͝͝͠͝*̸̴̵̴̴̵̴̸̵̴̴̴̴̵̴̴̵̸̡̡̢̪͍͉̫͕̠̞̠̺̟͓͕̦̻͓̞͚̼͉̞͇͓̞̪̙͍͙̺͉͇̦̘͍͎͍͎̪͕̙͇̞̟̘͓͉̼̞̘͆͛̐̔͐͆̈́́̔̔̓͌͐̿͑͆̐͑͊͐͒͋͐̓͑͋͌̿̓̾͊̒͋̈́͊͊̚͘̚̕̕̚͘̕̕͝͠͝͠͠*̵̴̸̴̴̴̸̴̵̴̴̡̢̢̡̺̙͙͇͙̞̼͍͚͓̙̫͇͇̘͎̙͙̝̙͔͙̻͐͑͌͐̓͆̓͌̿̐̽͑̒̈́̾͋̐̽̔͌̈́̀͛͆́͐̕͘͜͜͝͝͝*̸̵̵̸̴̸̴̸̸̵̸̴̸̵̸̢̢̡̼͎͕̼̠̼̙͇͎͚̟̝̦̫͉̟̪̟͉̝̦̘͕̼͔͔͔̙̫͎̫̙͕̝͉̫͍̻͑͒̔̈́̈́̓̐͑̐̾̒̽͌͋̈́͋̀̈́͊͑̓̓͒̓͊̈́͑͑̈́͆̽͊̈́̐̚̚̕̕̕͜͝͝͝͠*̸̵̴̴̸̸̸̸̸̸̸̸̴̵̡̡̡̢͚̘̼̟͙͎͍̘̺͍̼͓̫̦̻͚̝̟͓̻͎͚̟̼͔̫̺͉̫͓͕̞̺̟̓͆̐̈́̿̒̔͒͋͛̽͛̿͑͋̿͌͛͆̽̿͋̿̒̔͑̈́̿̚̚͘͘̚̚͘̕͜͜͝͠͝*̸̵̵̵̸̴̴̸̴̵̸̸̸̵̵̡͓̫͍̺͇͎̻͍̼̼̦͎͓̝̪͍̼̘̟͇̞͇̞͓͎̻̺͔̺̞̘̺̟̞̞̞͍̓̓͒́̈́̾́̽́͐̾̒̓̒̾̈́̔̽̽͌̔̒͐͌͊͒͑̈́̓͊͛̓̀̕͘͘͘͜͠͠͠*̵̴̵̵̸̵̴̴̵̴̵̸̵̴̸̢̡̡̠͍̝͉̘̦͍͇̠̠̙̠͇͓͖͍̙̼̙̦̦̻̙͓̺̙̘͓̪̻͕͔͇̼̪̘̼̔͆̈́̐͌̔̽̿̓͑͋̓̓͛̈́̓̈́͛͋̒͐̒̿̔̾͋̿̈́͑͌̚̕̚͘̚̕͝͠͠͝͝*̸̵̸̴̴̸̵̸̴̴̴̴̴̸̵̵̴̡̦̻̫̺̘͕̺̠̼͙̘̠̦͕̝͕̼̞̟̺͔̠͖͖͚̼͔͎͉̼̼̻̻̞͖̝͙͓͓̙͍͊͛̐̾̿͆̾́͐̓́͋̈́̒̓̽͊̀͑̓̓́͌̀́̓͆̒͆̽͆̒́͑͒̈́͑̓͒̕̕͜͜͜͜͝͠͝͝*̸̸̸̴̴̵̸̵̵̵̵̵̸̴̴̴̸̸̢̪̼͖̫̝͍͇̼̘͕̘͍̪̦͔̪̪̪̞͍̼͙̼͕͖̪̫̺̠̦͙̝̦͍͚̠̘̦͍̦͖̼͖͉̙͎̾̈́̓̾̿̓͋̽͛̔͊͌̈́̀͋̓̓̒̔̒̿͒͛͊̀͒͋̒͋̔͌͐͌͛̓͘̕̚̕̚͘̕͜͝͝͠͝͝͝͝͝͝*̸̸̴̵̸̸̵̸̴̵̴̸̸̸̸̡̡̟͓̠̙̦̪͔̘̞͖̫͕̦̼͔̻͕͉͓͓͉͓̙̼̙͓̪̼̪̫͍͎͇̻̞͛͋̈́̒̽͛̓̈́̒̀͊̔̒͆͛̓̓̾̔͐̽̒͊̽̐͒́̈́̔͑̓̕̚̚̕͜͜͠͠͝͝͝͝͠͠*̴̵̸̴̴̵̴̸̸̵̸̸̴̵̡̡̡̡̢͔̦̼̼̞͇͎̘͎̻͕̻̠͓̝̫̠͚̝͚͕͎͍͓͕̺͙͉̻̝͔̙͍̟͊̽̀̓̓͌͆́̈́͋͐͑̓̾͑͊͑͆̔̐͌̓̒͌͋̚͘͘̚͘͜͜͝͠͠͝͠͝͝͝͠͝*̸̴̵̴̴̵̴̸̵̴̴̴̴̵̴̴̵̸̡̡̢̪͍͉̫͕̠̞̠̺̟͓͕̦̻͓̞͚̼͉̞͇͓̞̪̙͍͙̺͉͇̦̘͍͎͍͎̪͕̙͇̞̟̘͓͉̼̞̘͆͛̐̔͐͆̈́́̔̔̓͌͐̿͑͆̐͑͊͐͒͋͐̓͑͋͌̿̓̾͊̒͋̈́͊͊̚͘̚̕̕̚͘̕̕͝͠͝͠͠*̵̴̸̴̴̴̸̴̵̴̴̡̢̢̡̺̙͙͇͙̞̼͍͚͓̙̫͇͇̘͎̙͙̝̙͔͙̻͐͑͌͐̓͆̓͌̿̐̽͑̒̈́̾͋̐̽̔͌̈́̀͛͆́͐̕͘͜͜͝͝͝*̸̵̵̸̴̸̴̸̸̵̸̴̸̵̸̢̢̡̼͎͕̼̠̼̙͇͎͚̟̝̦̫͉̟̪̟͉̝̦̘͕̼͔͔͔̙̫͎̫̙͕̝͉̫͍̻͑͒̔̈́̈́̓̐͑̐̾̒̽͌͋̈́͋̀̈́͊͑̓̓͒̓͊̈́͑͑̈́͆̽͊̈́̐̚̚̕̕̕͜͝͝͝͠*̸̵̴̴̸̸̸̸̸̸̸̸̴̵̡̡̡̢͚̘̼̟͙͎͍̘̺͍̼͓̫̦̻͚̝̟͓̻͎͚̟̼͔̫̺͉̫͓͕̞̺̟̓͆̐̈́̿̒̔͒͋͛̽͛̿͑͋̿͌͛͆̽̿͋̿̒̔͑̈́̿̚̚͘͘̚̚͘̕͜͜͝͠͝*̸̵̵̵̸̴̴̸̴̵̸̸̸̵̵̡͓̫͍̺͇͎̻͍̼̼̦͎͓̝̪͍̼̘̟͇̞͇̞͓͎̻̺͔̺̞̘̺̟̞̞̞͍̓̓͒́̈́̾́̽́͐̾̒̓̒̾̈́̔̽̽͌̔̒͐͌͊͒͑̈́̓͊͛̓̀̕͘͘͘͜͠͠͠*̵̴̵̵̸̵̴̴̵̴̵̸̵̴̸̢̡̡̠͍̝͉̘̦͍͇̠̠̙̠͇͓͖͍̙̼̙̦̦̻̙͓̺̙̘͓̪̻͕͔͇̼̪̘̼̔͆̈́̐͌̔̽̿̓͑͋̓̓͛̈́̓̈́͛͋̒͐̒̿̔̾͋̿̈́͑͌̚̕̚͘̚̕͝͠͠͝͝*̸̵̸̴̴̸̵̸̴̴̴̴̴̸̵̵̴̡̦̻̫̺̘͕̺̠̼͙̘̠̦͕̝͕̼̞̟̺͔̠͖͖͚̼͔͎͉̼̼̻̻̞͖̝͙͓͓̙͍͊͛̐̾̿͆̾́͐̓́͋̈́̒̓̽͊̀͑̓̓́͌̀́̓͆̒͆̽͆̒́͑͒̈́͑̓͒̕̕͜͜͜͜͝͠͝͝*̸̸̸̴̴̵̸̵̵̵̵̵̸̴̴̴̸̸̢̪̼͖̫̝͍͇̼̘͕̘͍̪̦͔̪̪̪̞͍̼͙̼͕͖̪̫̺̠̦͙̝̦͍͚̠̘̦͍̦͖̼͖͉̙͎̾̈́̓̾̿̓͋̽͛̔͊͌̈́̀͋̓̓̒̔̒̿͒͛͊̀͒͋̒͋̔͌͐͌͛̓͘̕̚̕̚͘̕͜͝͝͠͝͝͝͝͝͝*̸̸̴̵̸̸̵̸̴̵̴̸̸̸̸̡̡̟͓̠̙̦̪͔̘̞͖̫͕̦̼͔̻͕͉͓͓͉͓̙̼̙͓̪̼̪̫͍͎͇̻̞͛͋̈́̒̽͛̓̈́̒̀͊̔̒͆͛̓̓̾̔͐̽̒͊̽̐͒́̈́̔͑̓̕̚̚̕͜͜͠͠͝͝͝͝͠͠*̴̵̸̴̴̵̴̸̸̵̸̸̴̵̡̡̡̡̢͔̦̼̼̞͇͎̘͎̻͕̻̠͓̝̫̠͚̝͚͕͎͍͓͕̺͙͉̻̝͔̙͍̟͊̽̀̓̓͌͆́̈́͋͐͑̓̾͑͊͑͆̔̐͌̓̒͌͋̚͘͘̚͘͜͜͝͠͠͝͠͝͝͝͠͝*̸̴̵̴̴̵̴̸̵̴̴̴̴̵̴̴̵̸̡̡̢̪͍͉̫͕̠̞̠̺̟͓͕̦̻͓̞͚̼͉̞͇͓̞̪̙͍͙̺͉͇̦̘͍͎͍͎̪͕̙͇̞̟̘͓͉̼̞̘͆͛̐̔͐͆̈́́̔̔̓͌͐̿͑͆̐͑͊͐͒͋͐̓͑͋͌̿̓̾͊̒͋̈́͊͊̚͘̚̕̕̚͘̕̕͝͠͝͠͠*̵̴̸̴̴̴̸̴̵̴̴̡̢̢̡̺̙͙͇͙̞̼͍͚͓̙̫͇͇̘͎̙͙̝̙͔͙̻͐͑͌͐̓͆̓͌̿̐̽͑̒̈́̾͋̐̽̔͌̈́̀͛͆́͐̕͘͜͜͝͝͝*̸̵̵̸̴̸̴̸̸̵̸̴̸̵̸̢̢̡̼͎͕̼̠̼̙͇͎͚̟̝̦̫͉̟̪̟͉̝̦̘͕̼͔͔͔̙̫͎̫̙͕̝͉̫͍̻͑͒̔̈́̈́̓̐͑̐̾̒̽͌͋̈́͋̀̈́͊͑̓̓͒̓͊̈́͑͑̈́͆̽͊̈́̐̚̚̕̕̕͜͝͝͝͠*̸̵̴̴̸̸̸̸̸̸̸̸̴̵̡̡̡̢͚̘̼̟͙͎͍̘̺͍̼͓̫̦̻͚̝̟͓̻͎͚̟̼͔̫̺͉̫͓͕̞̺̟̓͆̐̈́̿̒̔͒͋͛̽͛̿͑͋̿͌͛͆̽̿͋̿̒̔͑̈́̿̚̚͘͘̚̚͘̕͜͜͝͠͝*̸̵̵̵̸̴̴̸̴̵̸̸̸̵̵̡͓̫͍̺͇͎̻͍̼̼̦͎͓̝̪͍̼̘̟͇̞͇̞͓͎̻̺͔̺̞̘̺̟̞̞̞͍̓̓͒́̈́̾́̽́͐̾̒̓̒̾̈́̔̽̽͌̔̒͐͌͊͒͑̈́̓͊͛̓̀̕͘͘͘͜͠͠͠*̵̴̵̵̸̵̴̴̵̴̵̸̵̴̸̢̡̡̠͍̝͉̘̦͍͇̠̠̙̠͇͓͖͍̙̼̙̦̦̻̙͓̺̙̘͓̪̻͕͔͇̼̪̘̼̔͆̈́̐͌̔̽̿̓͑͋̓̓͛̈́̓̈́͛͋̒͐̒̿̔̾͋̿̈́͑͌̚̕̚͘̚̕͝͠͠͝͝*̸̵̸̴̴̸̵̸̴̴̴̴̴̸̵̵̴̡̦̻̫̺̘͕̺̠̼͙̘̠̦͕̝͕̼̞̟̺͔̠͖͖͚̼͔͎͉̼̼̻̻̞͖̝͙͓͓̙͍͊͛̐̾̿͆̾́͐̓́͋̈́̒̓̽͊̀͑̓̓́͌̀́̓͆̒͆̽͆̒́͑͒̈́͑̓͒̕̕͜͜͜͜͝͠͝͝*̸̸̸̴̴̵̸̵̵̵̵̵̸̴̴̴̸̸̢̪̼͖̫̝͍͇̼̘͕̘͍̪̦͔̪̪̪̞͍̼͙̼͕͖̪̫̺̠̦͙̝̦͍͚̠̘̦͍̦͖̼͖͉̙͎̾̈́̓̾̿̓͋̽͛̔͊͌̈́̀͋̓̓̒̔̒̿͒͛͊̀͒͋̒͋̔͌͐͌͛̓͘̕̚̕̚͘̕͜͝͝͠͝͝͝͝͝͝*̸̸̴̵̸̸̵̸̴̵̴̸̸̸̸̡̡̟͓̠̙̦̪͔̘̞͖̫͕̦̼͔̻͕͉͓͓͉͓̙̼̙͓̪̼̪̫͍͎͇̻̞͛͋̈́̒̽͛̓̈́̒̀͊̔̒͆͛̓̓̾̔͐̽̒͊̽̐͒́̈́̔͑̓̕̚̚̕͜͜͠͠͝͝͝͝͠͠*̴̵̸̴̴̵̴̸̸̵̸̸̴̵̡̡̡̡̢͔̦̼̼̞͇͎̘͎̻͕̻̠͓̝̫̠͚̝͚͕͎͍͓͕̺͙͉̻̝͔̙͍̟͊̽̀̓̓͌͆́̈́͋͐͑̓̾͑͊͑͆̔̐͌̓̒͌͋̚͘͘̚͘͜͜͝͠͠͝͠͝͝͝͠͝*̸̴̵̴̴̵̴̸̵̴̴̴̴̵̴̴̵̸̡̡̢̪͍͉̫͕̠̞̠̺̟͓͕̦̻͓̞͚̼͉̞͇͓̞̪̙͍͙̺͉͇̦̘͍͎͍͎̪͕̙͇̞̟̘͓͉̼̞̘͆͛̐̔͐͆̈́́̔̔̓͌͐̿͑͆̐͑͊͐͒͋͐̓͑͋͌̿̓̾͊̒͋̈́͊͊̚͘̚̕̕̚͘̕̕͝͠͝͠͠*̵̴̸̴̴̴̸̴̵̴̴̡̢̢̡̺̙͙͇͙̞̼͍͚͓̙̫͇͇̘͎̙͙̝̙͔͙̻͐͑͌͐̓͆̓͌̿̐̽͑̒̈́̾͋̐̽̔͌̈́̀͛͆́͐̕͘͜͜͝͝͝*̸̵̵̸̴̸̴̸̸̵̸̴̸̵̸̢̢̡̼͎͕̼̠̼̙͇͎͚̟̝̦̫͉̟̪̟͉̝̦̘͕̼͔͔͔̙̫͎̫̙͕̝͉̫͍̻͑͒̔̈́̈́̓̐͑̐̾̒̽͌͋̈́͋̀̈́͊͑̓̓͒̓͊̈́͑͑̈́͆̽͊̈́̐̚̚̕̕̕͜͝͝͝͠*̸̵̴̴̸̸̸̡̡͚̘̼̟͙͎͍̘̺͍̼͓̫̦̓͆̐̈́̿̒̔͒͋͛̽͛̿͑̚̚͘͜͝͠.
x1=4
x2=-3
формула: a(x-x1)(x-x2)
в итоге имеем: (х-4)(х+3)=0