1.345乘0.345乘2.69-1.345的平方-1.345乘0.345的平方乘2
=1.345x0.345x2x1.345-1.345^2-1.345x0.345^2x2
=2x1.345x0.345(1.345-0.345)-1.345^2
=2x1.345x0.345-1.345^2
=1.345(0.69-1.345)
=-0.880975