S= 3+3/2+3/2^2+...+3/2^9
Tính S:
S = 3 + 3/2 + 3/2^2 + 3/2^3 + ... + 3/2^9
Tinh gia tri cua S:
S=3+3/2+3/2^2+.....+3/2^9
Tính toán
1) S = 1+2+3+4+...+n
2) S = 1*2*3...*n
3)S = 2+4+6+...+n
4)S = 1+3+5+...+n
5)S = 2*4*6...*n
6)S = 1-2+3-4+...+n
7)S = -1+2-3+4+...+n
8)S = 1+4+9+16+...+n*n
9)S = 1+9+25+...+( n mod 2 = 1)^2
10)S =4+16+...+( n mod 2 = 0)^2
11)S =5+10+15+...+ n mod 5 =0
12)S = 1+2-3+4+5-6+7+8-9...+n-(n mod 3 = 0 )
13)S = 1+2!+3!+4!...+n!
14)S =1+(1+2)+(1+2+3)+...+( tổng các số từ 1 tới )( i chạy từ 1 tới n)
15)S =1*2+2*3+4*5+...+(n-1)*n
HELP ME!
Tính tổng S :
S=3/2+3/2^2+...+3/2^9
ta có :
2.S=\(\frac{3}{2^2}+\frac{3}{2^3}+...+\frac{3}{2^{10}}\)
2.S-S=\(\left(\frac{3}{2^2}+\frac{3}{2^3}+...+\frac{3}{2^{10}}\right)-\left(\frac{3}{2}+\frac{3}{2^2}+...+\frac{3}{2^9}\right)\)
=>S=\(\frac{3}{2^{10}}-\frac{3}{2}\)
S=3+3/2+3/2^2+...+3/2^9
\(S=3+\frac{3}{2}+\frac{3}{2^2}+....+\frac{3}{2^9}\)
\(2S=6+3+\frac{3}{2}+....+\frac{3}{2^8}\)
=>\(2S-S=\left(6+3+\frac{3}{2}+...+\frac{3}{2^8}\right)-\left(3+\frac{3}{2}+\frac{3}{2^2}+....+\frac{3}{2^9}\right)\)
=>\(S=6-\frac{3}{2^9}=\frac{3069}{512}\)
tinh tong S= 3/2 +3/2^2 +3/2^3+......+3/2^9
\(2S=3+\frac{3}{2}+\frac{3}{2^2}+...+\frac{3}{2^8}\)
\(S=2S-S=3-\frac{3}{2^9}\)
Có S= 3/2 + 3/22 + 3/23 + ...+ 3/29 =>S*1/3 = 1/2 + 1/22 + 1/23 +...+ 1/29 =>S*1/3*2 = 1 + 1/2 + 1/22 +...+ 1/28 = S*2/3 => 2/3S - 1/3S = 1 + 1/2 + 1/22 +...+ 1/28 -(1/2 + 1/22 +...+ 1/29) => 1/3S = 1 + 1/2 + 1/22 +...+ 1/28 - 1/2 - 1/22 -...- 1/29 =>1/3S = 1 - 1/29 => S = 3 - 3/29
S= 3 + 3/2 + 3/2^2 + 3/2^3 + ... + 3/2^9
Đặt A=1+1/2+1/2.2+1/2.3+...+1/2.9
2A=2+1+1/2+1/2.2+...+1/2.8
Suy ra:A= 2A-A=2-1/2.9
S=3.(1-1/2.9)=3-1/6=17/6
TÍNH NHANH
1) S= 1/1*2+1/2*3+1/3*4+...+1/99*100
2) S= 3/1*3+3/3*5+2/5*7+...+2/97*99
3) S= 4/5*7+4/7*9+4/9*11+...+4/59*61
\(S=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+....+\frac{1}{99.100}\)
\(=1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+....+\frac{1}{99}-\frac{1}{100}\)
\(=1-\frac{1}{100}=\frac{99}{100}\)
tính S=3+3/2+3/2^2+...+3/2^9
Ta có:
S=3+3/2+3/2^2+3/2^3+...+3/2^9
2S=6+3+3/2+3/2^2+...+3/2^8
2S-S=(6+3+3/2+3/2^2+...+3/2^8)-(3+3/2+3/2^2+...+3/2^9)
S=6-2/512
S=3069/512
S=
tính tổng:
S=3+3/2+3/2^2+3/2^3+.....+3/2^9