So sanh 1/5+1/14+1/28+1/44+1/61+1/85+1/97 va 1/2
M=(1/4*9+1/9*14+1/14*19+...1/44*49)*1-3-5-7-9-...-49/89=-9/28
1 * 2 * 3 * 4 * 5 * 6 * 7 * 8 * 9 * 10 * 11 * 12 * 13 * 14 * 15 * 16 * 17 * 18 * 19 * 20 * 21 * 22 * 23 * 24 * 25 * 26 * 27 * 28 * 29 * 30 * 31 * 32 * 33 * 34 * 35 * 36 * 37 * 38 * 39 * 40 * 41 * 42 * 43 * 44 * 45 * 46 * 47 * 48 * 49 * 50 * 51 * 52 * 53 * 54 * 55 * 56 * 57 * 58 * 59 * 60 * 61 * 62 * 63 * 64 * 65 * 66 * 67 * 68 * 69 * 70 * 71 * 72 * 73 * 74 * 75 * 76 * 77 * 78 * 79 * 80 * 81 * 82 * 83 * 84 * 85 * 86 * 87 * 88 * 89 * 90 * 91 * 92 * 93 * 94 * 95 * 96 * 97 * 98 * 99 * 100 bằng bao nhiêu?
CMR : 1/3+1/5+1/13+1/14+1/15+1/61+1/62+1/63 < 5/6
( 1 / 4 . 9 + 1 / 9 . 14 + 1 / 14 . 19 + ... + 1 / 44 .49 ) . (1 - 3 - 5 - 7 - ... - 49) / 89 = ?
Tính:
3/5 + 3/11 - (-3/7) + (-2/97) - 1/35 - 3/4 + (-23/44)
1/7=8/-x
3x/9=2/6
4/2/5:(-33/10)+x=-1/5/6
(x-2/1/4):(-5/6)=3
-8:(4/1/5x+3/10)=4/4/9
(5,5x-44):(-3/2)=30
(13/10x-15).(-5/14)=3
1/3.(x+5/2)=-2
chu y dau( //)la so tap phan con dau( /) la phan so
TÍNH A=[(1/4*9)+(1/9*14)+(1/14*19)+...+(1/44*49)] x (1-3-5-7-...-49)/89
(1/4*9+1/9*14+...+1/44*49)*(1-3-5-7-...-49/89)
