✔ 最佳答案
1.
(1.01)²⁰
= (1 + 0.01)²⁰
= 1 + 20C1(0.01) + 20C2(0.01)² + 20C3(0.01)³ + 20C4(0.01)⁴ + ......
= 1 + 20(0.01) + 190(0.0001) + 1140(0.000001) + 4845(0.00000001) + ......
≈ 1 + 0.20 + 0.0190 + 0.001140 + 0.00004845
= 1.220 (至小數後三位)
====
2.
21¹⁸
= (20 + 1)¹⁸
= [20¹⁸ + 18C1(20)¹⁷ + ...... + 18C14(20)⁴] + [18C15(20)³ + 18C16(20)² + 18C17(20) + 1]
= (20)⁴ × [20¹⁴ + 18C1(20)¹³ + ...... + 18C14] + (816 ×8000 + 153 × 400 + 18 × 20 + 1)
= 10000 × 16 × [20¹⁴ + 18C1(20)¹³ + ...... + 18C14] + 6589561
21¹⁸ 除以10000 之餘數
= 6589561 除以 10000 之餘數
= 9561
====
3.
(x² - 2x + 2)¹⁰
= [(x² - 2x + 1) + 1]¹⁰
= [(x - 1)² + 1]¹⁰
= [(x - 1)²⁰ + 10C1(x - 1)¹⁸ + ...... + 10C8(x - 1)⁴] + 10C9(x- 1)² + 1
= (x - 1)³ [(x- 1)¹⁷ + 10C1(x - 1)¹⁵ + ...... + 10C8(x - 1)] + 9(x² - 2x+ 1) + 1
= (x - 1)³ [(x- 1)¹⁷ + 10C1(x - 1)¹⁵ + ...... + 10C8(x - 1)] + 9x² - 18x+ 10
(x - 1)³ 除 (x² - 2x + 2)¹⁰ 之餘式 = 9x² - 18x + 10
====
4.
(1 + 1)¹³ = (13C0 + 13C1+ ...... + 13C6) + (13C7 + 13C8+ ...... + 13C13)
(1 + 1)¹³ = (13C0 + 13C1+ ...... + 13C6) + (13C13 + ......+ 13C12 + 13C13)
因為 nCr = nCn-r
所以 (13C0 + 13C1+ ...... + 13C6) = (13C13 + ......+ 13C12 + 13C13)
故此 (1 + 1)¹³ = 2(13C0 + 13C1+ ...... + 13C6)
13C0 + 13C1 + ...... + 13C6
= 2¹³/2
= 4096
====
5.
8C0 - (1/2)8C1 + (1/4)8C2- (1/8)8C3 + ....... - (1/128)8C7 +(1/256)8C8
= 8C0(1)⁸ + 8C1(1)⁷(-1/2) + 8C2(1)⁶(-1/2)² + ....... + 8C7(1)(-1/2)⁷ + 8C8(-1/2)⁸
= [1 - (1/2)]⁸
= 1/256