不識做...
a, Expand (a+b)(a+3b)
b, 三角形ABD和BCD的底同樣是BD。ABD的高是a+3b,面積是a^2+4ab+3b^2。
找出BD的長度。(用a的result)
幾條考試的數學問題...
2007-01-18 11:58 am
回答 (2)
2007-01-18 12:13 pm
✔ 最佳答案
a. Expand (a+b)(a+3b)=a^2+3ab+ab+3b^2
=a^2+4ab+3b^2
b. let BD=X
X*(a+3b)/2=a^2+4ab+3b^2
X*(a+3b)/2=(a+b)(a+3b)
X=2*(a+b)(a+3b)/(a+3b)
X=2(a+b)
所以, BD=2(a+b)
2007-01-18 5:07 pm
a.(a+b)(a+3b)=a^2+3ab+ab+3b^2=a^2+4ab+3b^2
b.Area =base*height /2
a^2+4ab+3b^2 =BD*(a+3b)/2
(a+b)(a+3b)=BD*(a+3b)/2
=>BD=2(a+b)
b.Area =base*height /2
a^2+4ab+3b^2 =BD*(a+3b)/2
(a+b)(a+3b)=BD*(a+3b)/2
=>BD=2(a+b)
參考: Elmo Lecture note
收錄日期: 2021-04-13 16:12:30
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070118000051KK00405