(1/22-1)(1/32-1)...(1/92-1) (1/102-1)(40/11 x-20)
=40(x-3)+5
Những câu hỏi liên quan
Chứng minh rằng:
A = 1/3 + 1/32 + 1/33 + ..........+ 1/399 < 1/2
B = 3/12x 22 + 5/22 x 32 + 7/32 x 42 +............+ 19/92 x 102 < 1
C = 1/3 + 2/32 + 3/33 + 4/34 +.........+ 100/3100 ≤ 0
\(A=\dfrac{1}{3}+\dfrac{1}{3^2}+\dfrac{1}{3^3}+\dfrac{1}{3^4}+...+\dfrac{1}{3^{99}}\)
\(\Rightarrow\dfrac{A}{3}=\dfrac{1}{3^2}+\dfrac{1}{3^3}+\dfrac{1}{3^4}+...+\dfrac{1}{3^{100}}\)
\(\Rightarrow A-\dfrac{A}{3}=\dfrac{2A}{3}=\left(\dfrac{1}{3}+\dfrac{1}{3^2}+\dfrac{1}{3^3}+...+\dfrac{1}{3^{99}}\right)-\left(\dfrac{1}{3^2}+\dfrac{1}{3^3}+\dfrac{1}{3^4}+...+\dfrac{1}{3^{100}}\right)\)
\(\Rightarrow\dfrac{2A}{3}=\left(\dfrac{1}{3^2}-\dfrac{1}{3^2}\right)+\left(\dfrac{1}{3^3}-\dfrac{1}{3^3}\right)+...+\left(\dfrac{1}{3^{99}}-\dfrac{1}{3^{99}}\right)+\left(\dfrac{1}{3}-\dfrac{1}{3^{100}}\right)=\dfrac{1}{3}-\dfrac{1}{3^{100}}\)
\(\Rightarrow2A=3\cdot\left(\dfrac{1}{3}-\dfrac{1}{3^{100}}\right)\)
\(\Rightarrow\text{A}=\dfrac{1-\dfrac{1}{3^{99}}}{2}\)
\(\Rightarrow A=\dfrac{1}{2}-\dfrac{1}{2.3^{99}}< \dfrac{1}{2}\)
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tìm x
-2/3-1/3(2x-5)3/2
(-x-1/2)3/4+11/3
(31-1)(-1/2+5)0
x-20/11-20/13.15-20/15.17-...........-22/53.553/11
mk nhác tích lắm
bn nào giúp mk tick cho
Đọc tiếp
tìm x
-2/3-1/3(2x-5)=3/2
(-x-1/2)3/4+1=1/3
(31-1)(-1/2+5)=0
x-20/11-20/13.15-20/15.17-...........-22/53.55=3/11
mk nhác tích lắm
bn nào giúp mk tick cho
a) -2/3 - 1/3.(2x-5)=3/2
1/3.(2x-5)= -2/3 - 3/2
1/3.(2x-5) = -13/6
2x-5 = -13/6 : 1/3
2x-5 = -13/2
2x = -13/2 + 5 = -3/2
x=-3/2 : 2 = -3/4
Xl pn nh mk chỉ có thể giúp pn câu a thôi
vì nó hơi dài mỏi tay lém nên mk xl nkoa
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Thực hiện phép tính:
A) 7/38 x 9/11 +7/38 x 4/11 -7/38 x 2/11
B) 5/31 x 21/25 + 5/31 x -7/10 - 5/31 x 9/20
C) ( -2/3 + 3/7 ) : 4/5 + (-1/3 + 4/7 ) : 4/5
D) 5/9 : ( 1/11 -5/22 ) + 5/9 : ( 1/15 - 2/3 )
E) 3/14 : 1/28 -13/21 : 1/28 + 29/42 : 1/28 - 8
F) ( -40/51 x 0,32 x17/20) : 64/75
Đây là dấu x ( là nhân ) mọi người nhé
mong mn giúp em ạ
A) 7/38 x 9/11 +7/38 x 4/11 -7/38 x 2/11
=7/38.(9/11+4/11-2/11)
=7/38
B) 5/31 x 21/25 + 5/31 x -7/10 - 5/31 x 9/20
=5/31.(21/25-7/10-9/20)
=5/31.(-31/100)
=-1/20
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(31-1)(-1/2x+5)=0
x-20/11-20/13.15-20/15.17-...........-22/53.55=3/11
tìm x nhé các bn
bn nào giúp mk sẽ tick cho 3 tick
yêu các bn nhìu
a) \(\left(31-1\right)\left(\dfrac{-1}{2}x+5\right)=0\)
\(30\left(\dfrac{-1}{2}x+5\right)=0\)
\(\left(\dfrac{-1}{2}x+5\right)=0:30\)
\(\dfrac{-1}{2}x+5=0\)
\(\dfrac{-1}{2}x=0-5\)
\(\dfrac{-1}{2}x=-5\)
\(x=-5:\dfrac{-1}{2}\)
\(x=10\)
b) \(x-\dfrac{20}{11.13}-\dfrac{20}{13.15}-\dfrac{20}{15.17}-...-\dfrac{20}{53.55}=\dfrac{3}{11}\)
\(x-10\left(\dfrac{2}{11.13}+\dfrac{2}{13.15}+\dfrac{2}{15.17}+...+\dfrac{2}{53.55}\right)=\dfrac{3}{11}\)
\(x-10\left(\dfrac{1}{11}-\dfrac{1}{13}+\dfrac{1}{13}-\dfrac{1}{15}+\dfrac{1}{15}-\dfrac{1}{17}+...+\dfrac{1}{53}-\dfrac{1}{55}\right)=\dfrac{3}{11}\) \(x-10\left(\dfrac{1}{11}-\dfrac{1}{55}\right)=\dfrac{3}{11}\) \(x-10.\dfrac{4}{55}=\dfrac{3}{11}\) \(x-\dfrac{8}{11}=\dfrac{3}{11}\) \(x=\dfrac{3}{11}+\dfrac{8}{11}=1\)
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45/x - 1/3 + 28/51
x/20 - 2/5 = 40
(22-3).(3/4x+1)=
giải giúp giùm vs đag cần gấp
(1+2+3+...+1000+1001+1002+...+9999+10000).(32.1.2.3.4.5.6.7.8.9.10.311).(1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1+1-20+20-20+20-20+20+40-40+40-40+40-20-100+10000).32.33.34.(1-1).1.1.1.1.1.1.1.1.1.1.1.1.(1-2+3-4+5-6+7-8+9-10-100) = ?
Ai làm được tớ tick cho.
BT :Giải phương trình
a,(x+1)/1 + (2x+3)/3 + (3x+5)/5 +.........+(20x+39)/39 = 22+ 4/5 +5/6 +....40/39
b,(x-20)+(x-19)+(x-18)+......+100+101=101
14x + 54 = 82
175 + (30 - x) = 2001
1551- 10 (x + 1) = 55
5 . (x + 12) + 22 = 92
6 . (x + 23) + 40 = 100
14x + 54 = 82
14x = 28
x = 2
175 + (30 - x) = 2001
30 - x = 1826
x = 30 - 1826
x = - 1796
1551 - 10 ( x + 1 ) = 55
10(x + 1) = 1496
x + 1 = 149,6
x = 148,6
5 . (x + 12) + 22 = 92
5 . (x + 12) = 70
x + 12 = 14
x = 2
6 . (x + 23) + 40 = 100
6 . (x + 23) = 60
x + 23 = 10
x = - 13
\(14x+54=82\)
\(\Leftrightarrow14x=82-54\)
\(\Leftrightarrow14x=28\)
\(\Leftrightarrow x=2\)
Vậy \(x=2\)
\(175+\left(30-x\right)=2001\)
\(\Leftrightarrow30-x=2001-175\)
\(\Leftrightarrow30-x=1826\)
\(\Leftrightarrow x=-1796\)
Vậy \(x=-1796\)
\(1551-10\left(x+1\right)=55\)
\(\Leftrightarrow10.\left(x+1\right)=1551-55\)
\(\Leftrightarrow10.\left(x+1\right)=1496\)
\(\Leftrightarrow x+1=\frac{1496}{10}\)
\(\Leftrightarrow x=\frac{1486}{10}\)
Vậy \(x=\frac{1486}{10}\)
\(5.\left(x+12\right)+22=92\)
\(\Leftrightarrow5.\left(x+12\right)=70\)
\(\Leftrightarrow x+12=14\).
\(\Leftrightarrow x=2\)
Vậy \(x=2\)
\(6.\left(x+23\right)+40=100\)
\(\Leftrightarrow6.\left(x+23\right)=60\)
\(\Leftrightarrow x+23=10\)
\(\Leftrightarrow x=-13\)
Vậy \(x=-13\)
1.
a) 58.57+58.150-58.125 b)32.5-22.7+83.20190
c)2019+(-247)+(-53)-2019 d)13.70-50 [(19-32):2+23]
2.
a)x-36:18=12-5 b)92-(17+x)=72
c)720:[41-(2x+5)]=40 d) (x+2)3 -23=41
a) 58.57+58.150-58.125
=58.(57+150-125)
=58. 82
= 4756
b)32.5-22.7+83.20190
=9.5-4.7+83
=45-28+83
=100
c)2019+(-247)+(-53)-2019
=(2019-2019)+[ (-247)+(-53)]
0+(-300)
= -300
d)13.70-50 [(19-32):2+23]
=13.70-50[10:2+8]
=13.70-50.13
=13.(70-50)
=13.20
=260
2.
a)x-36:18=12-5
x-36:18=6
x-36=6.18
x-36=108
x=108+36
x= 144
b)92-(17+x)=72
17+x=92-72
17+x=20
x=20-17
x=3
c)720:[41-(2x+5)]=40
41-(2x+5)=720:40
41-(2x+5)= 18
2x+5=41-18
2x+5=23
2x=23-5
2x=18
x=18:2
x=9
d) (x+2)3 -23=41
(x+2)3 =41+23
(x+2)3 =64
=> (x+2)3 =43
=>x+2=4
=>x=4-2
=>x=2
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