2x² - 2x = -3 2x² - 2x + 1/4 = - 11/4 (x-1/2)² = - 11/4 本题在实数范围无解. x的平方+6x-11=0 x² + 6x + 9 = 20 (x+3)² = 20 x+3 = ± 2√5 x = - 3 ± 2√5
