ai giúp với
a, 12x35+35x182-35x94
b,125x98-125x46-52x25
c,17x39+116x83x17x23
d,1/2+1/6+1/12+1/20+....+1/100
K
Khách
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27 tháng 12 2015
125 x 98 + 125 x 46-52 x 25
125 x (98+46) - 52 x 25
125 x 144 -52 x25
18000 -1300
=16700
=
10 tháng 6 2016
a, 27 x 39 + 27 x 63 - 2 x 27
= 27 x ( 39 + 63 - 2 )
= 27 x 100
= 2700
b, 128 x 46 + 128 x 32 + 128x 22
= 128 x ( 46 + 32 + 22 )
= 128 x 100
= 12800
c, 12 x 35 + 35 x 182 - 35 x 94
= 35 x ( 12 + 182 - 94 )
= 35 x 100
= 3500
d, 456 : 2 x 18 + 456 : 3 - 102
= 228 x 18 + 152 - 102
= 4104 + 50
= 4154
HT
10 tháng 6 2016
\(\text{a, 27 x 39 + 27 x 63-2 x 27 =27 x (39+63-2) = 27 x 100 =2700}\)
\(\text{b, 128 x 46 +128 x 32 +128 x 22 =128 x (46+32+22)=128 x 100=12800}\)
\(\text{c , 12 x 35 +35 x 182 -35 x 94 =35 x (12+182-94)=35 x 100=3500.}\)
\(\text{d, 456:2 x 18 +456 :3 -102 =4140+152-102=4190}\)
2,
\(45-\left(x+9\right)=6\Rightarrow45-x-9-6\Rightarrow36-x=6\Rightarrow x=30\)
\(x+7-25=13\Rightarrow x-18=13\Rightarrow x=31\)
\(450:\left(x-19\right)=50\Rightarrow x-19=9\Rightarrow x=28\)
\(4\times\left(x+41\right)=400\Rightarrow x+41=100\Rightarrow x=59\)
\(x+73-26=76\Rightarrow x+47=76\Rightarrow x=31\)
X
14 tháng 2 2019
c)
\(\left(1-\frac{1}{2}\right)+\left(1-\frac{1}{6}\right)+....+\left(1-\frac{1}{42}\right)+\left(1-\frac{1}{56}\right)\)
\(\left(1+1+1+....+1+1\right)+\left(\frac{1}{1\times2}+\frac{1}{2\times3}+...+\frac{1}{6\times7}+\frac{1}{7\times8}\right)\)(Có 7 số 1)
\(7+1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+....+\frac{1}{6}-\frac{1}{7}+\frac{1}{7}-\frac{1}{8}\)
\(7+1-\frac{1}{8}=\frac{63}{8}\)
Gợi ý 1 bài c) còn d) e) cũng làm như vậy nhé
Chúc bạn học tốt !!!
25 tháng 10 2017
a,48x19+48x115+124x52
=48x(19+115)+124x52
=48x124+124x52
=124x(48+52)
=124x100
=12400
b,27x121-87x27+73x34
=27x(121-87)+73x34
=27x34+73x34
=34x(27+73)
=34x100
=3400
c,125x98-125x46-52x25
=125x(98-46)-52x25
=125x52-52x25
=52x(125-25)
=52x100
=5200
d,136x23+136x17-40x36
=136x(23+17)-40x36
=136x40-40x36
=40x(136-36)
=40x100
=4000
e,17x93+116x83+17x23
=17x93+17x23+116x83
=17x(93+23)+116x83
=17x116+116x83
=116x(17+83)
=116x100
=11600
g,19x27+47x81+19x20
=19x27+19x20+47x81
=19x(27+20)+47x81
=19x47+47x81
=47x(19+81)
=47x100
=4700
h,87x23+13x93+70x87
=87x23+70x87+13x93
=87x(23+70)+13x93
=87x93+13x93
=93x(87+13)
=93x100
=9300
Nhớ like mik nhé!^-^ Mất bao thời gian của mik đấy!
SS
2
DP
14 tháng 7 2017
Sửa đề : \(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{x\left(x+1\right)}=\frac{98}{100}\)
\(\Leftrightarrow\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{x\left(x+1\right)}=\frac{98}{100}\)
\(\Leftrightarrow\frac{2-1}{1\times2}+\frac{3-2}{2\times3}+\frac{4-3}{3\times4}+\frac{5-4}{4\times5}+....+\frac{\left(x+1\right)-x}{x\left(x+1\right)}=\frac{98}{100}\)
\(\Leftrightarrow\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+....+\frac{1}{x}-\frac{1}{\left(x+1\right)}=\frac{98}{100}\)
\(\Leftrightarrow\frac{1}{1}-\frac{1}{\left(x+1\right)}=\frac{98}{100}\)
\(\Leftrightarrow\frac{1}{\left(x+1\right)}=\frac{1}{1}-\frac{98}{100}\)
\(\Leftrightarrow\frac{1}{\left(x+1\right)}=\frac{1}{50}\)
\(\Leftrightarrow x=50-1=49\)
14 tháng 7 2017
Sửa đề: \(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{x\left(x+1\right)}=\frac{98}{100}\)
(=) \(\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{x\left(x+1\right)}=\frac{98}{100}\)
(=)\(1-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{x}-\frac{1}{x+1}=\frac{98}{100}\)
(=)\(1-\frac{1}{x+1}=\frac{98}{100}\)
(=)\(\frac{1}{x+1}=1-\frac{98}{100}\)
(=)\(\frac{1}{x+1}=\frac{1}{50}\)=> \(x+1=50\)
\(x=50-1\)
\(x=49\)
T_i_c_k cho mình nha,thanks you so much!
NT
2
LT
Lương Thị Vân Anh
CTVHS
6 tháng 2 2023
\(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+...+\dfrac{1}{110}\)
\(=\dfrac{1}{1\times2}+\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+...+\dfrac{1}{10\times11}\)
= 1 - \(\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+...+\dfrac{1}{10}-\dfrac{1}{11}\)
= \(1-\dfrac{1}{11}=\dfrac{10}{11}\)
30 tháng 6 2017
A= 1/2 + 1/6 + 1/12 + 1/20 + 1/30 + 1/42 + 1/56 + 1/72 + 1/90
=1/(1.2)+1/(2.3)+1/(3.4)+1/(4.5) +1/(5.6)+1/(6.7)+1/(7.8) +1/(8.9)+1/(9.10)
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5.+1/5-1/6... +1/9-1/10
=1-1/10
=9/10
KM
2
M
21 tháng 7 2017
D=1/2+1/6+1/12+...+1/90+1/100
D=(1/1x2+1/2x3+...+1/9x10)+1/100
D=(1-1/2+1/2-1/3+....+1/9-1/10)+1/100
D=(1-1/10)+1/100
D=9/10+1/100
D=91/100
21 tháng 7 2017
D=1/2+1/6+1/12+...+1/90+1/100
D=(1/1x2+1/2x3+...+1/9x10)+1/100
D=(1-1/2+1/2-1/3+....+1/9-1/10)+1/100
D=(1-1/10)+1/100
D=9/10+1/100
D=91/100
KM
6
T
23 tháng 7 2017
Đặt D = \(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+..+\frac{1}{100}\)
\(=1-\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{100}\)
\(=1-\frac{1}{100}\)
\(=\frac{99}{100}\)
12 x 35 + 35 x 182 - 35 x 94
= 35 x ( 12 + 182 - 94 )
= 35 x 100
= 3500
Ta có:
a) 12 x 35 + 35 x 182 - 35 x 94
= ( 12 + 182 - 94 ) x 35
= 100 x 35
= 3 500
b) Sửa đề:
125 x 98 - 125 x 46 - 52 x 125
= 125 x ( 98 - 46 - 52 )
= 125 x 0
= 0
c) 17 x 39 + 116 x 83 x 17 x 23
= 663 + 3764548
= 3765211
d) Sửa đề.
\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{110}\)
\(=\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{10.11}\)
\(=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+...+\frac{1}{10}-\frac{1}{11}\)
\(=\frac{1}{1}-\frac{1}{11}\)
\(=\frac{10}{11}\)
Bạn chép đề sai khá nhiều nhé!