用配方法解方程:2x的平方+5x-3=02x²+5x=3x²+5x/2=3/2x²+5x/2+25/16=49/16(x+5/4)²=49/16x+5/4=7/4 x+5/4=-7/4x=1/2 x=-3(x+3)(x+1)=6x+18(x+3)(x+1)-(6x+18)=0(x+3)(x+1)-6(x+3)=0(x+3)(x-5)=0x=-3 x=5
2x^2+5x+3=0,(x+1)(2x+3)=0,x1=-1, x2=-3/2.