(1)求值: lg 5 2 + 2 3 lg8+lg5•lg20+(lg2 ) 2

1个回答

  • (1) lg 5 2 +

    2

    3 lg8+lg5•lg20+(lg2 ) 2

    = 2lg5+

    2

    3 lg 2 3 +lg5(1+lg2)+(lg2 ) 2

    =2lg5+2lg2+lg5(1+lg2)+(lg2) 2
    =2(lg5+lg2)+lg5+lg5•lg2+(lg2) 2

    =2+lg5+lg2(lg5+lg2)=3.

    (2) (0.0081 ) -

    1

    4 -[3×(

    7

    8 ) 0 ] -1 × [8 1 -0.25 +(3

    3

    8 ) -

    1

    3 ] -

    1

    2 -10×0.02 7

    1

    3

    = ((0.3 ) 4 ) -

    1

    4 - 3 -1 ×[( 3 4 ) -

    1

    4 +(

    3

    2 ) -1 ] -

    1

    2 -10× ((0.3 ) 3 )

    1

    3

    =

    10

    3 -

    1

    3 (

    1

    3 +

    2

    3 ) -

    1

    2 -10•0.3

    =

    10

    3 -

    1

    3 -3

    =0.