用递等式计算(能简便计算的要写出简算过程).

1个回答

  • ①[3.2×(1-

    5

    8 )+3

    3

    5 ]×2

    1

    12 ,

    =[3

    1

    5 ×(1-

    5

    8 )+3

    3

    5 ]×2

    1

    12 ,

    =[3

    1

    5 ×

    3

    8 +3

    3

    5 ]×2

    1

    12 ,

    =(

    6

    5 +

    18

    5 )×

    25

    12 ,

    =

    24

    5 ×

    25

    12 ,

    =10;

    ②1

    3

    7 +2

    4

    15 +4

    4

    7 +3

    2

    15 ,

    =(1

    3

    7 +4

    4

    7 )+(2

    4

    15 +3

    2

    15 ),

    =6+5

    2

    3 ,

    =11

    2

    3 ;

    43

    97 ×99,

    =

    43

    97 ×(97+2),

    =

    43

    97 ×97+

    43

    97 ×2,

    =43+

    86

    97 ,

    =43

    86

    97 ;

    ④3.75×4

    2

    5 +1.6×3

    3

    4 ,

    =3.75×4.4+1.6×3.75,

    =3.75×(4.4+1.6),

    =3.75×6,

    =22.5;

    ⑤1÷2.5+2.5×0.4,

    =0.4+2.5×0.4,

    =0.4×(1+2.5),

    =0.4×3.5,

    =1.4;

    ⑥3

    2

    5 -1

    3

    4 -

    1

    4 ,

    =3

    2

    5 -(1

    3

    4 +

    1

    4 ),

    =3

    2

    5 -2,

    = 1

    2

    5 .