Các câu hỏi tương tự
Tìm X
(x-1/2)*(1/2+1/6+1/12+1/20+....+1/90)=1/3
2 x - 1/6 + 1/12 +1/20+...+1/90 = 3/11
Bài 1 :
S1= 1/6 + 1/12 + 1/20 + 1/42 + ...........+ 1/90 + 1/110
S2 = 1/2.15 + 1/15.3 + 1/3.21 + ............+ 6/87.90
Bài 2:
1) x . 5 + x : 100 = 25,-5
2) ( x-7 ) . ( 4x -8 ) = 0
3) 1/1/35 : (1/5 – 1/7 ) – 3/ 3x-2 = 1/1/14: ( 1/2 -1/7)
4 )1/1/3 + 1/6 + 1/10 + ……. + 2/ x.(x+1) = 16/9
Bài 1 :
S1= 1/6 + 1/12 + 1/20 + 1/42 + ...........+ 1/90 + 110
S2 = 1/2.15 + 1/15.3 + 1/3.21 + ............+ 6/87.90
Bài 2:
1) x . 5 + x : 100 = 25,-5
2) ( x-7 ) . ( 4x -8 ) = 0
3) 1/1/35 : (1/5 – 1/7 ) – 3/ 3x-2 = 1/1/14: ( 1/2 -1/7)
4 )1/1/3 + 1/6 + 1/10 + ……. + 2/ x.(x+1) = 16/9
Bài 1 :
S1= 1/6 + 1/12 + 1/20 + 1/42 + ...........+ 1/90 + 110
S2 = 1/2.15 + 1/15.3 + 1/3.21 + ............+ 6/87.90
Bài 2:
1) x . 5 + x : 100 = 25,-5
2) ( x-7 ) . ( 4x -8 ) = 0
3) 1/1/35 : (1/5 – 1/7 ) – 3/ 3x-2 = 1/1/14: ( 1/2 -1/7)
4 )1/1/3 + 1/6 + 1/10 + ……. + 2/ x.(x+1) = 16/9
Tính nhanh:
B=1/6+1/12+1/20+1/30+1/42+..........................1/90+1/100
H=[1-1/2] nhân [1-1/3] nhân ........................ nhân [1-1/2003] nhân[1-1/2004]
Tìm x (nhanh):
a, 1/6 + 1/12 + 1/20 + 1/30 + 1/42 + 1/56 + 1/72 + 1/90 + x = 3/5
b, 2/3.5 + 2/5.7 + ... + 2/13.15 + x = 1/3
c, 1/2 + 1/6 + 1/12 + 1/20 + ... + 1/x( x + 1) = 9/10
Ở cậu b dấu chấm là dấu nhân đấy nhé!!!
Giải ra nhé!!!
a ) 12,8 x 195 + 12,8 x 804 + 12,8
b) 1/2 +1/6 + 1/12+ 1/20+ 1/30 +1/42 +1/56 +1/72+ 1/90
1/2 + 1/6 + 1/12 +1/20 + ... +1/90