S2: (1/2+1)+(1/3+1)+(1/4+1)+..............+(1/s99+1)
giúp mk vs.
Các pạn ơi, giúp mk vs!
a) S1= 1+2+3+4+...+50
b) S2= 1/1:2 + 1/2:3 +1/3:4 +...+ 1/49:50 (phân số)
a) Số số hạng là :
( 50 - 1 ) : 1 + 1 = 50 ( số )
Tổng là :
( 50 + 1 ) x 50 : 2 = 1275
Đáp số : 1275
b) không hiểu
Cho S1 = 1+2; S2 = 3+4+5; S3 = 6+7+8+9; S4 = 10+11+12+13+14… Hãy tính S99?
S1=1+2
s2=3+4+5
s3=6+7+8+9
s4=10+11+12+13+14
tính s99=?
Giúp mk vs ae :
S2 = 4+4^3+4^5+4^7+....................+4^99
Bài 2
3^102 - 1 chia hết cho 8
4^101 - 1 chia hết cho 3 và 5
1+ 1/2(1+2) + 1/3(1+2+3) +1/4(1+2+3+4) +....+1/100(1+2+3+..+100)
Ai giúp mk vs .....
Tk mình đi mọi người mình bị âm nè!
Ai tk mình mình tk lại cho
Tk mình đi mọi người mình bị âm nè!
Ai tk mình mình tk lại cho
Tính:(1/2-1)(1/3-1)(1/4-1)...1/100
giải giúp mk vs mk cần gấp
Sửa đề
\(\left(\frac{1}{2}-1\right)\left(\frac{1}{3}-1\right)\left(\frac{1}{4}-1\right)....\left(\frac{1}{100}-1\right)\)
\(=\)\(\left(-\frac{1}{2}\right).\left(-\frac{2}{3}\right).\left(-\frac{3}{4}\right)...\left(-\frac{99}{100}\right)\) ( 99 phân số )
\(=\)\(\frac{\left(-1\right)\left(-2\right)\left(-3\right)...\left(-99\right)}{2.3.4...100}\)
\(=\)\(-\frac{1}{100}\)
\(\left(\frac{1}{2}-1\right)\left(\frac{1}{3}-1\right)\left(\frac{1}{4}-1\right)...\left(\frac{1}{100}-1\right)\)
\(=-\frac{1}{2}.\frac{2}{3}.\frac{3}{4}...\frac{98}{99}.\frac{99}{100}\)
\(=-\frac{1}{100}\)
(1+2/1)*(1+2/2)*(1+2/3)*(1+2/4)*..*(1+2/26)*(1+2/26)giúp mk vs nha mk đg cần gấp
(1/2^2).(1/3^2).(1/4^2)....(1/99^2)
giúp mk vs mk đang cần gấp
Đặt A =1/2^2 .1/3^2.1/4^2. ... . 1/99^2
2A=1/2.1/2^2.1/2^3. ... . 1/98^2
2A-A= (1/2.1/2^2.1/2^3. ... . 1^98^2)-(1/2^2.1/3^2.1/4^2. ... . 1/99^2)
A=1/2-1/99^2
Tính B= 1+1/2(1+2)+1/3(1+2+3)+1/4(1+2+3+4)+...+1/20(1+2+3+...+20)
giúp mk vs!!!
Viết lại đề bài
\(B=1+\frac{1}{2\left(1+2\right)}+\frac{1}{3\left(1+2+3\right)}+\frac{1}{4\left(1+2+3+4\right)}+...+\frac{1}{20\left(1+2+3+4...+20\right)}\)
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