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(5-2x)(x+4)
運用上題化簡
(5-2x)(x+4)-(2x+7)
數學題 幫我計計
2007-02-21 2:52 am
回答 (3)
2007-02-21 3:06 am
✔ 最佳答案
(5-2x)(x+4)= 5x+20-2x^2-8x
= -3x+20-2x^2
= -2x^2+20-3x <---------------(你鍾意有就有, 冇就冇, 只是方便我計)
(5-2x)(x+4)-(2x+7)
= -2x^2+20-3x-(2x+7)
= -2x^2+20-3x-2x-7
= -2x^2+13-5x
2007-02-20 19:07:24 補充：
上面個個計錯左, (5-2x)(x+4)-(2x+7)佢睇左(5-2x)(x+4)-(2x-7)
參考: -2x^2 = -2 x二次
2007-02-21 3:26 am
(5-2x)(x+4)
=(5-2x)(x)+(5-2x)(4)
=5x-2x(2次方)+20-8x
=5x-8x-2x(2次方)+20
=-3x-2x(2次方)+20
(5-2x)(x+4)-(2x+7)
=(5-2x)(x)+(5-2x)(+4)-(5-2x)(2x)+(5-2x)(7)
=5x-2x(2次方)+(20)-(8)-(10x)-(4x)+(35)-(14x)
=(5-2x)(x)+(5-2x)(4)
=5x-2x(2次方)+20-8x
=5x-8x-2x(2次方)+20
=-3x-2x(2次方)+20
(5-2x)(x+4)-(2x+7)
=(5-2x)(x)+(5-2x)(+4)-(5-2x)(2x)+(5-2x)(7)
=5x-2x(2次方)+(20)-(8)-(10x)-(4x)+(35)-(14x)
2007-02-21 2:57 am
(5-2x)(x+4)
=5x+20-2x^2-8x
=20-3x-2x^2
(5-2x)(x+4)-(2x-7)
=20-3x-2x^2-2x+7
=27-5x-2x^2
=5x+20-2x^2-8x
=20-3x-2x^2
(5-2x)(x+4)-(2x-7)
=20-3x-2x^2-2x+7
=27-5x-2x^2
收錄日期: 2021-04-18 20:09:03
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070220000051KK03069