720 、2 、120 、4、 24、 12、 6、 48 、( ) 、 ( ) Find the rules,

720 、2 、120 、4、 24、 12、 6、 48 、( ) 、 ( ) Find the rules,

Divide these numbers into two groups, 720, 120, 24, 6 and (2). The rule is to divide from 6 to 3
2. 4, 12, 48, (240), multiply from 2 to 5

1、．0,6,24,（ ）,120
2、1／125,1／16,1／3,1,（ ）
3、 24／84,12／42,10／35,8／28,（ ）,2／7
4、-2,5,24,61,（ ）

0,6,24,（60 ）,120
1／125,1／16,1／3,1,（1 ）
24／84,12／42,10／35,8／28,（ 4/14）,2／7
-2,5,24,61,（128 ）

1/2-1/6-24/1-1/120

The general formula of 1,2,6,24

1=1
2=1*2
6=1*2*3
24=1*2*3*4
an=n!=1*2*3*…… *n

A1 = 1, A2 = 1 / 2, A3 = 1 / 6, A4 = 1 / 24, A5 = 1 / 120

an=1/(n*1/a(n-1))

Write the sequence 1, 5, 23, 119, 719 A general term formula of

1=1*2-1
5=1*2*3-1
23=1*2*3*4-1
So an = (n + 1)! - 1

Calculation: 56 + 2324 + 5960 + 119120 + 209210 + 8384

56+2324+5960+119120+209210+8384，=1-16+1-124+1-160+1-1120+1-1210+1-184，=6-524-3120-160，=6-14，=234．

The general formula of 1,2,6,24120
emergency

An = n! From the known recurrence formula an = n * a (n-1), a (n-1) = (n-1) * a (n-2) All the way to A1, we get an = n * (n-1) (n-2) (n-3) *2 * 1 = n! Note: a (n-1) denotes item n-1

Triangle function value, cos720 degree

Original formula = cos (2 × 360 ° + 0 °)
=cos0°
=1

Beijing Normal University edition of mathematics synchronous reading, Grade 7 25.26 can't do, ask the answer! Please, please!
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