X² + 2x + 1 = 3 + 1
Выдели полный квадрат ​

x² + 2x = 3+ 1 - 1

x² + 2x = 3

x² + 2x - 3 = 0

D = b² - 4ac = 4 - 4 - ( -3 ) = 4 + 12 = 16 √D = 4

x1 = - b + √D / 2a = - 2 + 4 /2 = 1

x2 = -b - √D/ 2a = - 2 - 4 /2 = - 3

x1 = 1; x2 = - 3