计算1.2345*0.2345*2.469-1.2345^3-1.2345*0.2345^2

1.2345*0.2345*2.469-1.2345^3-1.2345*0.2345^2
=-1.2345*(-0.2345*2.469+1.2345^2+0.2345^2)
=-1.2345*(1.2345-0.2345)^2
=-1.2345*1^2
=-1.2345