图
3x² + 6x - 4 = 0x² + 2x = 4/3x² + 2x + 1 = 7/3(x + 1)² = 7/3x + 1 = ± √21 / 3x = - 1 ± √21 / 3
3x^2+6x-4=0x=(-6±√(6^2+4*3*4))/6x=(-3±√21)/3望采纳，谢谢！
