А) 32 – t2 = д) 121a2 – 49 б) 122 – (4a)2 = е) 25в2 – 64f2 =
в) 144r2 – 16 = ж) 81a2 – 100 =
г) 9с2 – 100x4 = з) 36 – 16a2 =
3. Разложите на множители
а) 4 + 12f + 9f 2 =
б) 25 + 80x + 81x 2 =
в) 4х 2 + 28ху + 49у2 =
г) m 2 + 16 m n + 64n2 =

от -∞ до 3  

(-∞;3]                                    график функции:    ⬇⬇⬇⬇⬇

*̸̵̵̵̸̴̴̸̴̵̸̸̸̵̵̡͓̫͍̺͇͎̻͍̼̼̦͎͓̝̪͍̼̘̟͇̞͇̞͓͎̻̺͔̺̞̘̺̟̞̞̞͍̓̓͒́̈́̾́̽́͐̾̒̓̒̾̈́̔̽̽͌̔̒͐͌͊͒͑̈́̓͊͛̓̀̕͘͘͘͜͠͠͠*̵̴̵̵̸̵̴̴̵̴̵̸̵̴̸̢̡̡̠͍̝͉̘̦͍͇̠̠̙̠͇͓͖͍̙̼̙̦̦̻̙͓̺̙̘͓̪̻͕͔͇̼̪̘̼̔͆̈́̐͌̔̽̿̓͑͋̓̓͛̈́̓̈́͛͋̒͐̒̿̔̾͋̿̈́͑͌̚̕̚͘̚̕͝͠͠͝͝*̸̵̸̴̴̸̵̸̴̴̴̴̴̸̵̵̴̡̦̻̫̺̘͕̺̠̼͙̘̠̦͕̝͕̼̞̟̺͔̠͖͖͚̼͔͎͉̼̼̻̻̞͖̝͙͓͓̙͍͊͛̐̾̿͆̾́͐̓́͋̈́̒̓̽͊̀͑̓̓́͌̀́̓͆̒͆̽͆̒́͑͒̈́͑̓͒̕̕͜͜͜͜͝͠͝͝*̸̸̸̴̴̵̸̵̵̵̵̵̸̴̴̴̸̸̢̪̼͖̫̝͍͇̼̘͕̘͍̪̦͔̪̪̪̞͍̼͙̼͕͖̪̫̺̠̦͙̝̦͍͚̠̘̦͍̦͖̼͖͉̙͎̾̈́̓̾̿̓͋̽͛̔͊͌̈́̀͋̓̓̒̔̒̿͒͛͊̀͒͋̒͋̔͌͐͌͛̓͘̕̚̕̚͘̕͜͝͝͠͝͝͝͝͝͝*̸̸̴̵̸̸̵̸̴̵̴̸̸̸̸̡̡̟͓̠̙̦̪͔̘̞͖̫͕̦̼͔̻͕͉͓͓͉͓̙̼̙͓̪̼̪̫͍͎͇̻̞͛͋̈́̒̽͛̓̈́̒̀͊̔̒͆͛̓̓̾̔͐̽̒͊̽̐͒́̈́̔͑̓̕̚̚̕͜͜͠͠͝͝͝͝͠͠*̴̵̸̴̴̵̴̸̸̵̸̸̴̵̡̡̡̡̢͔̦̼̼̞͇͎̘͎̻͕̻̠͓̝̫̠͚̝͚͕͎͍͓͕̺͙͉̻̝͔̙͍̟͊̽̀̓̓͌͆́̈́͋͐͑̓̾͑͊͑͆̔̐͌̓̒͌͋̚͘͘̚͘͜͜͝͠͠͝͠͝͝͝͠͝*̸̴̵̴̴̵̴̸̵̴̴̴̴̵̴̴̵̸̡̡̢̪͍͉̫͕̠̞̠̺̟͓͕̦̻͓̞͚̼͉̞͇͓̞̪̙͍͙̺͉͇̦̘͍͎͍͎̪͕̙͇̞̟̘͓͉̼̞̘͆͛̐̔͐͆̈́́̔̔̓͌͐̿͑͆̐͑͊͐͒͋͐̓͑͋͌̿̓̾͊̒͋̈́͊͊̚͘̚̕̕̚͘̕̕͝͠͝͠͠*̵̴̸̴̴̴̸̴̵̴̴̡̢̢̡̺̙͙͇͙̞̼͍͚͓̙̫͇͇̘͎̙͙̝̙͔͙̻͐͑͌͐̓͆̓͌̿̐̽͑̒̈́̾͋̐̽̔͌̈́̀͛͆́͐̕͘͜͜͝͝͝*̸̵̵̸̴̸̴̸̸̵̸̴̸̵̸̢̢̡̼͎͕̼̠̼̙͇͎͚̟̝̦̫͉̟̪̟͉̝̦̘͕̼͔͔͔̙̫͎̫̙͕̝͉̫͍̻͑͒̔̈́̈́̓̐͑̐̾̒̽͌͋̈́͋̀̈́͊͑̓̓͒̓͊̈́͑͑̈́͆̽͊̈́̐̚̚̕̕̕͜͝͝͝͠*̸̵̴̴̸̸̸̸̸̸̸̸̴̵̡̡̡̢͚̘̼̟͙͎͍̘̺͍̼͓̫̦̻͚̝̟͓̻͎͚̟̼͔̫̺͉̫͓͕̞̺̟̓͆̐̈́̿̒̔͒͋͛̽͛̿͑͋̿͌͛͆̽̿͋̿̒̔͑̈́̿̚̚͘͘̚̚͘̕͜͜͝͠͝*̸̵̵̵̸̴̴̸̴̵̸̸̸̵̵̡͓̫͍̺͇͎̻͍̼̼̦͎͓̝̪͍̼̘̟͇̞͇̞͓͎̻̺͔̺̞̘̺̟̞̞̞͍̓̓͒́̈́̾́̽́͐̾̒̓̒̾̈́̔̽̽͌̔̒͐͌͊͒͑̈́̓͊͛̓̀̕͘͘͘͜͠͠͠*̵̴̵̵̸̵̴̴̵̴̵̸̵̴̸̢̡̡̠͍̝͉̘̦͍͇̠̠̙̠͇͓͖͍̙̼̙̦̦̻̙͓̺̙̘͓̪̻͕͔͇̼̪̘̼̔͆̈́̐͌̔̽̿̓͑͋̓̓͛̈́̓̈́͛͋̒͐̒̿̔̾͋̿̈́͑͌̚̕̚͘̚̕͝͠͠͝͝*̸̵̸̴̴̸̵̸̴̴̴̴̴̸̵̵̴̡̦̻̫̺̘͕̺̠̼͙̘̠̦͕̝͕̼̞̟̺͔̠͖͖͚̼͔͎͉̼̼̻̻̞͖̝͙͓͓̙͍͊͛̐̾̿͆̾́͐̓́͋̈́̒̓̽͊̀͑̓̓́͌̀́̓͆̒͆̽͆̒́͑͒̈́͑̓͒̕̕͜͜͜͜͝͠͝͝*̸̸̸̴̴̵̸̵̵̵̵̵̸̴̴̴̸̸̢̪̼͖̫̝͍͇̼̘͕̘͍̪̦͔̪̪̪̞͍̼͙̼͕͖̪̫̺̠̦͙̝̦͍͚̠̘̦͍̦͖̼͖͉̙͎̾̈́̓̾̿̓͋̽͛̔͊͌̈́̀͋̓̓̒̔̒̿͒͛͊̀͒͋̒͋̔͌͐͌͛̓͘̕̚̕̚͘̕͜͝͝͠͝͝͝͝͝͝*̸̸̴̵̸̸̵̸̴̵̴̸̸̸̸̡̡̟͓̠̙̦̪͔̘̞͖̫͕̦̼͔̻͕͉͓͓͉͓̙̼̙͓̪̼̪̫͍͎͇̻̞͛͋̈́̒̽͛̓̈́̒̀͊̔̒͆͛̓̓̾̔͐̽̒͊̽̐͒́̈́̔͑̓̕̚̚̕͜͜͠͠͝͝͝͝͠͠*̴̵̸̴̴̵̴̸̸̵̸̸̴̵̡̡̡̡̢͔̦̼̼̞͇͎̘͎̻͕̻̠͓̝̫̠͚̝͚͕͎͍͓͕̺͙͉̻̝͔̙͍̟͊̽̀̓̓͌͆́̈́͋͐͑̓̾͑͊͑͆̔̐͌̓̒͌͋̚͘͘̚͘͜͜͝͠͠͝͠͝͝͝͠͝*̸̴̵̴̴̵̴̸̵̴̴̴̴̵̴̴̵̸̡̡̢̪͍͉̫͕̠̞̠̺̟͓͕̦̻͓̞͚̼͉̞͇͓̞̪̙͍͙̺͉͇̦̘͍͎͍͎̪͕̙͇̞̟̘͓͉̼̞̘͆͛̐̔͐͆̈́́̔̔̓͌͐̿͑͆̐͑͊͐͒͋͐̓͑͋͌̿̓̾͊̒͋̈́͊͊̚͘̚̕̕̚͘̕̕͝͠͝͠͠*̵̴̸̴̴̴̸̴̵̴̴̡̢̢̡̺̙͙͇͙̞̼͍͚͓̙̫͇͇̘͎̙͙̝̙͔͙̻͐͑͌͐̓͆̓͌̿̐̽͑̒̈́̾͋̐̽̔͌̈́̀͛͆́͐̕͘͜͜͝͝͝*̸̵̵̸̴̸̴̸̸̵̸̴̸̵̸̢̢̡̼͎͕̼̠̼̙͇͎͚̟̝̦̫͉̟̪̟͉̝̦̘͕̼͔͔͔̙̫͎̫̙͕̝͉̫͍̻͑͒̔̈́̈́̓̐͑̐̾̒̽͌͋̈́͋̀̈́͊͑̓̓͒̓͊̈́͑͑̈́͆̽͊̈́̐̚̚̕̕̕͜͝͝͝͠*̸̵̴̴̸̸̸̸̸̸̸̸̴̵̡̡̡̢͚̘̼̟͙͎͍̘̺͍̼͓̫̦̻͚̝̟͓̻͎͚̟̼͔̫̺͉̫͓͕̞̺̟̓͆̐̈́̿̒̔͒͋͛̽͛̿͑͋̿͌͛͆̽̿͋̿̒̔͑̈́̿̚̚͘͘̚̚͘̕͜͜͝͠͝*̸̵̵̵̸̴̴̸̴̵̸̸̸̵̵̡͓̫͍̺͇͎̻͍̼̼̦͎͓̝̪͍̼̘̟͇̞͇̞͓͎̻̺͔̺̞̘̺̟̞̞̞͍̓̓͒́̈́̾́̽́͐̾̒̓̒̾̈́̔̽̽͌̔̒͐͌͊͒͑̈́̓͊͛̓̀̕͘͘͘͜͠͠͠*̵̴̵̵̸̵̴̴̵̴̵̸̵̴̸̢̡̡̠͍̝͉̘̦͍͇̠̠̙̠͇͓͖͍̙̼̙̦̦̻̙͓̺̙̘͓̪̻͕͔͇̼̪̘̼̔͆̈́̐͌̔̽̿̓͑͋̓̓͛̈́̓̈́͛͋̒͐̒̿̔̾͋̿̈́͑͌̚̕̚͘̚̕͝͠͠͝͝*̸̵̸̴̴̸̵̸̴̴̴̴̴̸̵̵̴̡̦̻̫̺̘͕̺̠̼͙̘̠̦͕̝͕̼̞̟̺͔̠͖͖͚̼͔͎͉̼̼̻̻̞͖̝͙͓͓̙͍͊͛̐̾̿͆̾́͐̓́͋̈́̒̓̽͊̀͑̓̓́͌̀́̓͆̒͆̽͆̒́͑͒̈́͑̓͒̕̕͜͜͜͜͝͠͝͝*̸̸̸̴̴̵̸̵̵̵̵̵̸̴̴̴̸̸̢̪̼͖̫̝͍͇̼̘͕̘͍̪̦͔̪̪̪̞͍̼͙̼͕͖̪̫̺̠̦͙̝̦͍͚̠̘̦͍̦͖̼͖͉̙͎̾̈́̓̾̿̓͋̽͛̔͊͌̈́̀͋̓̓̒̔̒̿͒͛͊̀͒͋̒͋̔͌͐͌͛̓͘̕̚̕̚͘̕͜͝͝͠͝͝͝͝͝͝*̸̸̴̵̸̸̵̸̴̵̴̸̸̸̸̡̡̟͓̠̙̦̪͔̘̞͖̫͕̦̼͔̻͕͉͓͓͉͓̙̼̙͓̪̼̪̫͍͎͇̻̞͛͋̈́̒̽͛̓̈́̒̀͊̔̒͆͛̓̓̾̔͐̽̒͊̽̐͒́̈́̔͑̓̕̚̚̕͜͜͠͠͝͝͝͝͠͠*̴̵̸̴̴̵̴̸̸̵̸̸̴̵̡̡̡̡̢͔̦̼̼̞͇͎̘͎̻͕̻̠͓̝̫̠͚̝͚͕͎͍͓͕̺͙͉̻̝͔̙͍̟͊̽̀̓̓͌͆́̈́͋͐͑̓̾͑͊͑͆̔̐͌̓̒͌͋̚͘͘̚͘͜͜͝͠͠͝͠͝͝͝͠͝*̸̴̵̴̴̵̴̸̵̴̴̴̴̵̴̴̵̸̡̡̢̪͍͉̫͕̠̞̠̺̟͓͕̦̻͓̞͚̼͉̞͇͓̞̪̙͍͙̺͉͇̦̘͍͎͍͎̪͕̙͇̞̟̘͓͉̼̞̘͆͛̐̔͐͆̈́́̔̔̓͌͐̿͑͆̐͑͊͐͒͋͐̓͑͋͌̿̓̾͊̒͋̈́͊͊̚͘̚̕̕̚͘̕̕͝͠͝͠͠*̵̴̸̴̴̴̸̴̵̴̴̡̢̢̡̺̙͙͇͙̞̼͍͚͓̙̫͇͇̘͎̙͙̝̙͔͙̻͐͑͌͐̓͆̓͌̿̐̽͑̒̈́̾͋̐̽̔͌̈́̀͛͆́͐̕͘͜͜͝͝͝*̸̵̵̸̴̸̴̸̸̵̸̴̸̵̸̢̢̡̼͎͕̼̠̼̙͇͎͚̟̝̦̫͉̟̪̟͉̝̦̘͕̼͔͔͔̙̫͎̫̙͕̝͉̫͍̻͑͒̔̈́̈́̓̐͑̐̾̒̽͌͋̈́͋̀̈́͊͑̓̓͒̓͊̈́͑͑̈́͆̽͊̈́̐̚̚̕̕̕͜͝͝͝͠*̸̵̴̴̸̸̸̸̸̸̸̸̴̵̡̡̡̢͚̘̼̟͙͎͍̘̺͍̼͓̫̦̻͚̝̟͓̻͎͚̟̼͔̫̺͉̫͓͕̞̺̟̓͆̐̈́̿̒̔͒͋͛̽͛̿͑͋̿͌͛͆̽̿͋̿̒̔͑̈́̿̚̚͘͘̚̚͘̕͜͜͝͠͝*̸̵̵̵̸̴̴̸̴̵̸̸̸̵̵̡͓̫͍̺͇͎̻͍̼̼̦͎͓̝̪͍̼̘̟͇̞͇̞͓͎̻̺͔̺̞̘̺̟̞̞̞͍̓̓͒́̈́̾́̽́͐̾̒̓̒̾̈́̔̽̽͌̔̒͐͌͊͒͑̈́̓͊͛̓̀̕͘͘͘͜͠͠͠*̵̴̵̵̸̵̴̴̵̴̵̸̵̴̸̢̡̡̠͍̝͉̘̦͍͇̠̠̙̠͇͓͖͍̙̼̙̦̦̻̙͓̺̙̘͓̪̻͕͔͇̼̪̘̼̔͆̈́̐͌̔̽̿̓͑͋̓̓͛̈́̓̈́͛͋̒͐̒̿̔̾͋̿̈́͑͌̚̕̚͘̚̕͝͠͠͝͝*̸̵̸̴̴̸̵̸̴̴̴̴̴̸̵̵̴̡̦̻̫̺̘͕̺̠̼͙̘̠̦͕̝͕̼̞̟̺͔̠͖͖͚̼͔͎͉̼̼̻̻̞͖̝͙͓͓̙͍͊͛̐̾̿͆̾́͐̓́͋̈́̒̓̽͊̀͑̓̓́͌̀́̓͆̒͆̽͆̒́͑͒̈́͑̓͒̕̕͜͜͜͜͝͠͝͝*̸̸̸̴̴̵̸̵̵̵̵̵̸̴̴̴̸̸̢̪̼͖̫̝͍͇̼̘͕̘͍̪̦͔̪̪̪̞͍̼͙̼͕͖̪̫̺̠̦͙̝̦͍͚̠̘̦͍̦͖̼͖͉̙͎̾̈́̓̾̿̓͋̽͛̔͊͌̈́̀͋̓̓̒̔̒̿͒͛͊̀͒͋̒͋̔͌͐͌͛̓͘̕̚̕̚͘̕͜͝͝͠͝͝͝͝͝͝*̸̸̴̵̸̸̵̸̴̵̴̸̸̸̸̡̡̟͓̠̙̦̪͔̘̞͖̫͕̦̼͔̻͕͉͓͓͉͓̙̼̙͓̪̼̪̫͍͎͇̻̞͛͋̈́̒̽͛̓̈́̒̀͊̔̒͆͛̓̓̾̔͐̽̒͊̽̐͒́̈́̔͑̓̕̚̚̕͜͜͠͠͝͝͝͝͠͠*̴̵̸̴̴̵̴̸̸̵̸̸̴̵̡̡̡̡̢͔̦̼̼̞͇͎̘͎̻͕̻̠͓̝̫̠͚̝͚͕͎͍͓͕̺͙͉̻̝͔̙͍̟͊̽̀̓̓͌͆́̈́͋͐͑̓̾͑͊͑͆̔̐͌̓̒͌͋̚͘͘̚͘͜͜͝͠͠͝͠͝͝͝͠͝*̸̴̵̴̴̵̴̸̵̴̴̴̴̵̴̴̵̸̡̡̢̪͍͉̫͕̠̞̠̺̟͓͕̦̻͓̞͚̼͉̞͇͓̞̪̙͍͙̺͉͇̦̘͍͎͍͎̪͕̙͇̞̟̘͓͉̼̞̘͆͛̐̔͐͆̈́́̔̔̓͌͐̿͑͆̐͑͊͐͒͋͐̓͑͋͌̿̓̾͊̒͋̈́͊͊̚͘̚̕̕̚͘̕̕͝͠͝͠͠*̵̴̸̴̴̴̸̴̵̴̴̡̢̢̡̺̙͙͇͙̞̼͍͚͓̙̫͇͇̘͎̙͙̝̙͔͙̻͐͑͌͐̓͆̓͌̿̐̽͑̒̈́̾͋̐̽̔͌̈́̀͛͆́͐̕͘͜͜͝͝͝*̸̵̵̸̴̸̴̸̸̵̸̴̸̵̸̢̢̡̼͎͕̼̠̼̙͇͎͚̟̝̦̫͉̟̪̟͉̝̦̘͕̼͔͔͔̙̫͎̫̙͕̝͉̫͍̻͑͒̔̈́̈́̓̐͑̐̾̒̽͌͋̈́͋̀̈́͊͑̓̓͒̓͊̈́͑͑̈́͆̽͊̈́̐̚̚̕̕̕͜͝͝͝͠*̸̵̴̴̸̸̸̸̸̸̸̸̴̵̡̡̡̢͚̘̼̟͙͎͍̘̺͍̼͓̫̦̻͚̝̟͓̻͎͚̟̼͔̫̺͉̫͓͕̞̺̟̓͆̐̈́̿̒̔͒͋͛̽͛̿͑͋̿͌͛͆̽̿͋̿̒̔͑̈́̿̚̚͘͘̚̚͘̕͜͜͝͠͝*̸̵̵̵̸̴̴̸̴̵̸̸̸̵̵̡͓̫͍̺͇͎̻͍̼̼̦͎͓̝̪͍̼̘̟͇̞͇̞͓͎̻̺͔̺̞̘̺̟̞̞̞͍̓̓͒́̈́̾́̽́͐̾̒̓̒̾̈́̔̽̽͌̔̒͐͌͊͒͑̈́̓͊͛̓̀̕͘͘͘͜͠͠͠*̵̴̵̵̸̵̴̴̵̴̵̸̵̴̸̢̡̡̠͍̝͉̘̦͍͇̠̠̙̠͇͓͖͍̙̼̙̦̦̻̙͓̺̙̘͓̪̻͕͔͇̼̪̘̼̔͆̈́̐͌̔̽̿̓͑͋̓̓͛̈́̓̈́͛͋̒͐̒̿̔̾͋̿̈́͑͌̚̕̚͘̚̕͝͠͠͝͝*̸̵̸̴̴̸̵̸̴̴̴̴̴̸̵̵̴̡̦̻̫̺̘͕̺̠̼͙̘̠̦͕̝͕̼̞̟̺͔̠͖͖͚̼͔͎͉̼̼̻̻̞͖̝͙͓͓̙͍͊͛̐̾̿͆̾́͐̓́͋̈́̒̓̽͊̀͑̓̓́͌̀́̓͆̒͆̽͆̒́͑͒̈́͑̓͒̕̕͜͜͜͜͝͠͝͝*̸̸̸̴̴̵̸̵̵̵̵̵̸̴̴̴̸̸̢̪̼͖̫̝͍͇̼̘͕̘͍̪̦͔̪̪̪̞͍̼͙̼͕͖̪̫̺̠̦͙̝̦͍͚̠̘̦͍̦͖̼͖͉̙͎̾̈́̓̾̿̓͋̽͛̔͊͌̈́̀͋̓̓̒̔̒̿͒͛͊̀͒͋̒͋̔͌͐͌͛̓͘̕̚̕̚͘̕͜͝͝͠͝͝͝͝͝͝*̸̸̴̵̸̸̵̸̴̵̴̸̸̸̸̡̡̟͓̠̙̦̪͔̘̞͖̫͕̦̼͔̻͕͉͓͓͉͓̙̼̙͓̪̼̪̫͍͎͇̻̞͛͋̈́̒̽͛̓̈́̒̀͊̔̒͆͛̓̓̾̔͐̽̒͊̽̐͒́̈́̔͑̓̕̚̚̕͜͜͠͠͝͝͝͝͠͠*̴̵̸̴̴̵̴̸̸̵̸̸̴̵̡̡̡̡̢͔̦̼̼̞͇͎̘͎̻͕̻̠͓̝̫̠͚̝͚͕͎͍͓͕̺͙͉̻̝͔̙͍̟͊̽̀̓̓͌͆́̈́͋͐͑̓̾͑͊͑͆̔̐͌̓̒͌͋̚͘͘̚͘͜͜͝͠͠͝͠͝͝͝͠͝*̸̴̵̴̴̵̴̸̵̴̴̴̴̵̴̴̵̸̡̡̢̪͍͉̫͕̠̞̠̺̟͓͕̦̻͓̞͚̼͉̞͇͓̞̪̙͍͙̺͉͇̦̘͍͎͍͎̪͕̙͇̞̟̘͓͉̼̞̘͆͛̐̔͐͆̈́́̔̔̓͌͐̿͑͆̐͑͊͐͒͋͐̓͑͋͌̿̓̾͊̒͋̈́͊͊̚͘̚̕̕̚͘̕̕͝͠͝͠͠*̵̴̸̴̴̴̸̴̵̴̴̡̢̢̡̺̙͙͇͙̞̼͍͚͓̙̫͇͇̘͎̙͙̝̙͔͙̻͐͑͌͐̓͆̓͌̿̐̽͑̒̈́̾͋̐̽̔͌̈́̀͛͆́͐̕͘͜͜͝͝͝*̸̵̵̸̴̸̴̸̸̵̸̴̸̵̸̢̢̡̼͎͕̼̠̼̙͇͎͚̟̝̦̫͉̟̪̟͉̝̦̘͕̼͔͔͔̙̫͎̫̙͕̝͉̫͍̻͑͒̔̈́̈́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     .

35х = 3у + 5
49х = 4у + 9

35х = 3у + 5
3у=35х-5
3у=5(7х-1)
у=5(7х-1)/3

49х = 4*5(7х-1)/3 + 9
49х=140х-20+27/3
49х*3=140х+7
147х-140х=7
7х=7
х=1
у=5(7*1-1)/3
у=5*6/3
у=5*2
у=105х - 4у = 5 | *(-5)
-25х + 20у = -25

а теперь складываем строки системы уравнений
25х - 18 у = 75
-25х + 20у = -25

0х +2у = 50
т. е. 2у = 50
у = 25

для того чтобы найти х, подставляем полученное значение у в любое уравнение
5х -4*25 = 5
5х - 100 = 5
5х = 5 + 100
5х = 105
х= 105/5
х = 21

ответ
х=21
у=25.

 -3u+5v=1.5 домножим обе части уравнения на -3,получаем

9u-15v=4.5

система принимает вид. можем применить метод сложения (аналогично А)

11u+15v=1.9

9u-15v=4.5

2х-3у = -8

х=7-4у

2(7-4у) -3у = -8
х=7-4у

14-8у-3у+8=0
х=7-4у

22=11у
х=7-4у

у=2
х=7-8

у=2
х=-1

20v=6.4

v=0.32