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teddyyip1997二星初級會員
2011-9-6 21:28#1
1,
28(x+y)^2 - 7(x-y)^2
=
=
=7(3x+y)(x+3y)
---------------------------------
2,
12v-12v^2 - 6u+3u^2
=
=
=7(3x+y)(x+3y)
---------------------------------
3,
-p^2q^2+^4
=
=
=(r+pq)(r-pq)(r^2+pq)
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36661124二轉會員
2011-9-6 22:07#2
1.28(x+y)^2 - 7(x-y)^2
= 7[4(x+y)^2 - (x-y)^2 ]
= 7[(4x² +8xy +4y² -x² +2xy -y²]
=7 [3x² +10xy +3y²]
=7(3x+y)(x+3y)
3,
-p^2q^2+r^4
= [r^2]^2 - (pq)^2
=[r²-pq] [r² +pq]
第3題係咪打少野或者打錯野
p q 個degree . 問題得deg 2 ,但ans有deg 4
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36661124二轉會員
2011-9-6 22:10#3
2,
12v-12v^2 - 6u+3u^2
=3(u^2 -4v^2 +4v- 2u)
=3[(u-2v)(u+2v)+2(2v-u)]
=3[(u-2v)(u+2v)-2( u - 2v)]
=3(u-2v)(u+2v-2)
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teddyyip1997二星初級會員
2011-9-6 22:44#4
本帖最後由 teddyyip1997 於 11-9-6 10:45 PM 編輯
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第2題我打錯答案:redface:
但係你都答得啱~:smilie_;):
第3題係我想睇下自已個答案啱唔啱~(我以為本書錯左):smilie_:o:
點知原來係我錯:smilie_:(:
你做既又好易而又啱,讃~:smilie_:):