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
125x98+125x46 -52x25
125 x 98 + 125 x 46-52 x 25
125 x (98+46) - 52 x 25
125 x 144 -52 x25
18000 -1300
=16700
=
a) 27x39+27x63-2x27
b) 128 x46+128x32+128x22
c)12x35+35x182-35x94
d) 456:2x18+456:3-102
Tìm X , biết
1< 45 -( X+9 ) = 6
2 < ( X +7) -25=13
3 < 450: (X -19)=50
4< 4 x ( X + 41) = 400
5 < (X+73 ) - 26= 76
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
\(\text{a, 27 x 39 + 27 x 63-2 x 27 =27 x (39+63-2) = 27 x 100 =2700}\)
\(\text{b, 128 x 46 +128 x 32 +128 x 22 =128 x (46+32+22)=128 x 100=12800}\)
\(\text{c , 12 x 35 +35 x 182 -35 x 94 =35 x (12+182-94)=35 x 100=3500.}\)
\(\text{d, 456:2 x 18 +456 :3 -102 =4140+152-102=4190}\)
2,
\(45-\left(x+9\right)=6\Rightarrow45-x-9-6\Rightarrow36-x=6\Rightarrow x=30\)
\(x+7-25=13\Rightarrow x-18=13\Rightarrow x=31\)
\(450:\left(x-19\right)=50\Rightarrow x-19=9\Rightarrow x=28\)
\(4\times\left(x+41\right)=400\Rightarrow x+41=100\Rightarrow x=59\)
\(x+73-26=76\Rightarrow x+47=76\Rightarrow x=31\)
Bài 3 Tính
a) A=1+1/2+1/2^2+1/2^3+...+1/2^99+1/2^100+1/2^101
b) B=1+1/3+1/3^2+1/3^3+...+1/3^100
c)1/2+5/6+11/12+19/20+29/30+41/42+55/56
d)2/3+14/15+34/35+...+9998/9999
e)1/2+5/6+11/12+...+9989/9990
Các bạn giúp mình với mình đang cần gấp lắm
Ai giúp mình làm bài này mình cho 10 tick luôn các bạn giúp mình với huhuhuhu
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 !!!
tinh nhanh
a,48x19+48x115+124x52
b.27x121-87x27+73x34
c.125x98-125x46-52x25
d,136x23+136x17-40x36
e,17x93+116x83+17x23
g,19x27+47x81+19x20
h,87x23+13x93+70x87
cac ban oi nhung so nao tach ra de tinh nhanh duoc thi cac ban hay tach ra nha cam on nhieu ai nhanh mik cho 1 like
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!
tìm x :
1/2 + 1/6 + 1/12 + 1/20 +..... +2/x.(x + 1) = 98/100
giúp mình nha
Sửa đề : \(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{x\left(x+1\right)}=\frac{98}{100}\)
\(\Leftrightarrow\frac{1}{1.2}+\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+...+\frac{1}{x\left(x+1\right)}=\frac{98}{100}\)
\(\Leftrightarrow\frac{2-1}{1\times2}+\frac{3-2}{2\times3}+\frac{4-3}{3\times4}+\frac{5-4}{4\times5}+....+\frac{\left(x+1\right)-x}{x\left(x+1\right)}=\frac{98}{100}\)
\(\Leftrightarrow\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+....+\frac{1}{x}-\frac{1}{\left(x+1\right)}=\frac{98}{100}\)
\(\Leftrightarrow\frac{1}{1}-\frac{1}{\left(x+1\right)}=\frac{98}{100}\)
\(\Leftrightarrow\frac{1}{\left(x+1\right)}=\frac{1}{1}-\frac{98}{100}\)
\(\Leftrightarrow\frac{1}{\left(x+1\right)}=\frac{1}{50}\)
\(\Leftrightarrow x=50-1=49\)
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!
1/2 + 1/6 + 1/12 + 1/20 ..... + 1/110
ai giúp e dk? em đg cần gấp. E cảm ơn
\(\dfrac{1}{2}+\dfrac{1}{6}+\dfrac{1}{12}+\dfrac{1}{20}+...+\dfrac{1}{110}\)
\(=\dfrac{1}{1\times2}+\dfrac{1}{2\times3}+\dfrac{1}{3\times4}+\dfrac{1}{4\times5}+...+\dfrac{1}{10\times11}\)
= 1 - \(\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+...+\dfrac{1}{10}-\dfrac{1}{11}\)
= \(1-\dfrac{1}{11}=\dfrac{10}{11}\)
\(\dfrac{1}{1.2}+\dfrac{1}{2.3}+\dfrac{1}{3.4}+\dfrac{1}{4.5}+...+\dfrac{1}{10.11}=1-\dfrac{1}{2}+\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+\dfrac{1}{4}-\dfrac{1}{5}+...+\dfrac{1}{10}-\dfrac{1}{11}=1-\dfrac{1}{11}=\dfrac{10}{11}\)
1/2 + 1/6 + 1/12 + 1/20 + 1/30 + 1/42 + 1/56 + 1/72 + 1/90 = x - ( 2 + 4 + ... + 100 )
Mk cần gấp ai nhanh mk tick
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
\(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}=x-\left(2+4+..+100\right)\)
Gọi \(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+\frac{1}{30}+\frac{1}{42}+\frac{1}{56}+\frac{1}{72}+\frac{1}{90}\)là \(A\)
\(\left(2+4+...+100\right)\)là \(B\). Ta có :
\(A=\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+\frac{1}{4\cdot5}+\frac{1}{5\cdot6}+\frac{1}{6\cdot7}+\frac{1}{7\cdot8}+\frac{1}{8\cdot9}+\frac{1}{9\cdot10}\)
\(A=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+....+\frac{1}{9}-\frac{1}{10}\)
\(A=\frac{1}{1}-\frac{1}{10}=\frac{9}{10}\)
Số số hạng của \(B\)là: \(\left(100-2\right)\div2+1=50\)
Tổng của \(B\)là: \(\left(2+100\right)\times50\div2=2550\)
\(\Rightarrow\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{90}=x-\left(2+4+..+100\right)=\frac{9}{10}=x-2550\)
\(\Rightarrow x=2550+\frac{9}{10}=2550+0,9=2550,9\)
D=1/2+1/6+1/12+1/20+...+1/100
tính D
ai trả lời đầu tiên mình sẽ tích và kb
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
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
D=1/2+1/6+1/12+1/20+...+1/100
tính D
ai trả lời đầu tiên mình sẽ tích và kb
Đặt D = \(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+..+\frac{1}{100}\)
\(=1-\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{100}\)
\(=1-\frac{1}{100}\)
\(=\frac{99}{100}\)
Đặt D = \(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{100}\)
\(=1-\left(\frac{1}{2}+\frac{1}{6}+\frac{1}{12}+\frac{1}{20}+...+\frac{1}{100}\right)\)
\(=1-\frac{1}{100}\)
\(=\frac{99}{100}\)