1.2345×0.2345×2.469-1.2345³-1.2345×0.2345²

这么简单?我也是初一的 设1.2345为a 你们应该学了因式分解了吧,你把a带进去就可以算了.

1.2345×0.2345×2.469-1.2345³-1.2345×0.2345²
=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

令x=1.2345
x*(x-1)*(2x) - x^3 - x*(x-1)^2
=x*(x-1)*(2x-x+1) - x^3
=x*(x-1)*(x+1) - x^3
=x*(x^2-1)-x^3
=(x^3-x)-x^3
=-x
=-1.2345我才初一，看不懂、、、、、原式 = 1.2345*(0.2345×2.469-1.2345&...