(-1+1/2)(-1+1/3)(-1+1/4)...(-1+1/299)
(-1+1/2)(-1+1/3)(-1+1/4)...(-1+1/299)
CMR: 1/151+1/152+1/153+…+1/300=1-1/2+1/3-1/4+…+1/299-1/300
CMR:S=1/2+1/3+1/4+…1/2013
A = 1 + \(\dfrac{1}{2^2}+\dfrac{1}{2^3}+\dfrac{1}{2^4}+...+\dfrac{1}{299}\)
( 3/10/99 + 4/11/119 - 5/8/299 ) * ( 1/2 -1/3 -1/6 ) =?
=(3/10/99+4/11/119-5/8/299)*(3/6-2/6-1/6)
=(3/10/99+4/11/119-5/8/299)*(1/6-1/6)
=(3/10/99+4/11/119-5/8/299)*0
=0
Tìm x biết : 1/2×3 + 1/3×4 + 1/4×5 +. ..+1/x+(x+1)=299/600
Ai làm đúng mình tick cho
B= (3 10/99 +4 11/199 -5 8/299).(1/2-1/3-1/6)
Tính tích P = ( 1- 1/2). (1- 1/3). (1- 1/4) ... ( 1 -1/99)
Chứng tỏ rằng : 1/101 +1/102+ ... +1/299 + 1/300 > 2/3
\(\left(1-\dfrac{1}{2}\right).\left(1-\dfrac{1}{3}\right).\left(1-\dfrac{1}{4}\right)...\left(1-\dfrac{1}{99}\right)\)
\(=\dfrac{1}{2}.\dfrac{2}{3}.\dfrac{3}{4}....\dfrac{98}{99}=\dfrac{1.2.3...98}{2.3.4...99}=\dfrac{1}{99}\)
cho a= 1/2*3/4*5/6*...*299/300. chứng tỏ 1/25<a<1/17
Bài 299: Tính
1) 1/3 x 1/2 x 3/7
2) 5/4 x 1/3 + 1/7
3) 8 x ( 8/9-2/3 )
4) 5/6 x 48/20 x 1/2
5) ( 2/5 + 3/4 + x 8
6) 10 x ( 1/2 - 1/5 )
Trình bày rõ cách làm giúp ạ!!
1) 1/3 x 1/2 x 3/7 = 3/42 = 1/14
2) 5/4 x 1/3 +1/7 = 5/12 + 1/7 = 35/84 + 12/84 = 47/84
3) 8 x ( 8/9 - 2/3 ) = 8 x 2/9 = 16/9
4) 5/6 x 48/20 x 1/2 = 240/240 = 1
5) ( 2/5 + 3/4 ) + 8 = 23/20 + 8 = 23//20 + 160/20 = 183/20
6) 10 x ( 1/2 - 1/5 ) = 10 x 3/10 = 10/1 x 3/10 = 30/10 = 3