1､x²+3x+1=0
x=(-3±√(3²-4)/2
=(-3±√5)/2
2､3x²+5(2x+1)=0
3x²+10x+5=0
x=(-10±√(10²-4*3*5)/(2*3)
=(-10±√40)/(2*3)
=(-5±√10)/3
3､x²+2(√2-1)x+3-2√2=0
x={2(√2-1)±√[(2√2-2)²-4(3-2√2)]}/2
=[2(√2-1)±√(4√2)]/2
=(√2-1)±√√2公式法啊公式法x=[-b±√(b²-4ac)]/(2a)更正3x²+2(√2-1)x+3-2√2=0x={-2(√2-1)±√[(2√2-2)²-4(3-2√2)]}/2=[-2(√2-1)±√(8-8√2-4-12-8√2)]/2=-2(√2-1)/2=1-√2