問數學題10~

1.　 (8x² y²) / (25x z³) * (20yz) / (16y² z²)

　= (8xy²) / (25 z³) * (20) / (16yz)

　= [(8xy²)(20)] / [(25 z³)(16yz)]

　= 160xy² / 400yz^4

　= 2xy / 5z^4

2. 　(3x - 3y/4x) * (3ax/ax-ay)

　= [3 (x-y) / 4x)] * [ 3ax/ a(x-y)]

　= [3 (x-y)*3ax] / [4x * a(x-y)]

　= 9 / 4

3. ???

4. 　(6x²/y) / (2x/y²)

　= (6x²/y) * (y²/2x)

　= (6x² y²) / (2xy)

　= 3xy


2006-12-02 11:07:48 補充：
再用d時間諗過，問題3 應該係打錯左1個n做m.如果將問題改為咁就ok:　(3m-2n)/(5n m)² * (2m 10n)/(6m-4n)= (3m-2n)/(5n m)² * (m 5n)/(3m-2n)= [(3m-2n)(m 5n)]/[(5n m)²(3m-2n)= 1/(5n m)

4.

6x²/y 除 2x/y²
= 6x²/y x y²/2x
約簡
=3xy