請詳細列出計算步驟和答案.
1)-32p^2+68pr-21r^2
2)a)把4x^2-17xy-15y^2分解為因式.
b)利用(a)部的結果,把4x^2-17xy-15y^2+24x+18y分解為因式.
唔該曬~THX
MATHS
2007-09-26 7:14 pm
回答 (1)
2007-09-28 12:35 am
✔ 最佳答案
1) -32p^2 + 68pr - 21r^2
= -(32p^2 - 68pr + 21r^2)
= -(4p-7r)(8p-3r)
做這條數, 首先將 32 和 21 的因數寫出來
32: 1, 2, 4, 8, 16, 32
21: 1, 3, 7, 21
然後再配對, 結果可以得出
(-3)(4) + (-7)(8)
= -12 - 56
= -68
2a)
4x^2 - 17xy - 15y^2
= (4x+3y)(x-5y)
2b)
4x^2 - 17xy - 15y^2 + 24x + 18y
= (4x+3y)(x-5y) + 24x + 18y
= (4x+3y)(x-5y) + 6(4x+3y)
= (4x+3y) [ (x-5y) + 6 ]
參考: I am a Maths tutor
收錄日期: 2021-04-13 19:03:58
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