maths　f.3

(√2+√3) / (√9+√6)

=(√2+√3) / (3+√6)

=(√2+√3)(3-√6) / (3+√6)(3-√6)

=[3√2+3√3-√(2*6)-√(3*6)] / (9 - 6)

=(3√2 + 3√3 - 2√3 - 3√2) / 3

=√3 / 3 or 1/√3
(不過通常唔會放開方三响份母度架)


2.
[2√3/(√3-√2)] -[ 3√2/(√2+√3)
=[2√3(√3+√2)/(√3-√2)(√3+√2)] - [ 3√2(√2-√3)/(√2+√3)(√2-√3)]
=[(2*3 + 2√3√2)/(3-2)] - [(3*2 - 3√2√3)/(2-3)]
= 6 + 2√6 + (6-3√6)
=12-√6
=√6(2√6 - 1)

2007-06-05 11:49:10 補充：
To : SR好抱歉, 我數學冇你咁好. 又係新手, 所以先會做左 d 多餘野不過有時 d 教科書背後 d 答案會怪怪地..所以先俾多個答案人啫..

As follow:


圖片參考：http://img14.imgspot.com/u/07/153/09/264102162921517324.JPG


2007-06-03 23:39:44 補充：
To applefung927:畫蛇添足係冇用~~

2007-06-05 15:47:51 補充：
To applefung927:sorry~P.S.我係小六~~