Question

加油~~

感覺是有什麼特別的算法，就是不用爆開來算（但想不出來

】 = ( ²º¹ − 1 ) ר¯¯¯*-* ( ** − 1) × (−1) × (−1) ***
(-1)
ㄨㄨ
【演練24】

Answer 1

✨ Jawaban Terbaik ✨

qn

(1 - ½²)(1 - ⅓²)(1 - ¼²)⋯(1 - ⅒²)
= (1- ½)(1 + ½)(1- ⅓)(1 + ⅓)(1 - ¼)(1 + ¼)⋯(1 - ⅒)(1 + ⅒)
= (1/2 · 3/2) · (2/3 · 4/3) · (3/4 · 5/4) ⋯ (9/10 · 11/10)
= 1/2 · (3/2 · 2/3) · (4/3 · 3/4) ⋯ (10/9 · 9/10) · 11/10
= 1/2 · 11/10
= 11/20

Answer 2

Ian

a²-b²=(a-b)(a+b)
1-1/2²=1/2•3/2

(1/2•3/2)×(2/3•4/3)×(3/4•5/4)×.....×(9/10•11/10)
=1/2•11/10
=11/20