Х2 -1=3
х2-4=0
(х-2)(х+2)=0
х=2 и х=-2
Сумма корней 2+(-2)=0
115. 116, 161, 611, 123, 132, 213, 231, 312, 321
118. а) 3/37, 3/73, 7/33, б) 3/3377, 3/3737, 3/3773, 3/7337, 3/7373, 3/7733, 7/3337, 7/3373, 7/3733, 7/7333, 33/377, 33/737, 33/773, 37/337, 37/373,
37/733, 73/337, 73/373, 73/733, 77/333.
119. 1/13, 2/13, 3/13, 4/13, 5/13, 6/13
1) x² - 12x + 25 = x² - 12x + 36 - 36 + 25 = (x² - 12x + 36) - 11 = (x - 6)² - 11
2) x² - 6x + 12 = x² - 6x + 9 - 9 + 12 = (x² - 6x + 9) + 3 = (x - 3)² + 3
Решение:
-15а+3+4а=2а+35-21а
-11а+3=-19а+35
-11а+19а=35-3
8а=32
а=4
Ответ:4