Question

计算下列各式值
（1）(2x)

1

4

(-3x

1

4

y-

1

3

)÷[(-27)

2

3

x-

1

2

y-

2

3

]（2）log2

7 48

+log212-

1

2

log242．

Answer 1

（1）(2x)

1

4

(-3x

1

4

y-

1

3

)÷[(-27)

2

3

x-

1

2

y-

2

3

]
=-(2

1

4

×31-3×

2

3

)•x

1

4

+

1

4

+

1

2

 •y-

1

3

+

2

3

=-

4 2

3

x

3	y

．
（2）log2

7 48

+log212-

1

2

log242=

1

2

log

72

-

1

2

log

(24×3)2

+

log

(22×3)2

 -

1

2

log

(2×3×7)2

=

1

2

log

72

-

1

2

log

242

-

1

2

log

32

+

log

222

+

log

32

 -

1

2

log

22

-

1

2

log

32

-

1

2

log

72

=-

1

2

×4+2-

1

2

=-

1

2

．