A=1/1+2+1/1+2+3+1/1+2+3+4+...+1/1+2+3+...+9
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TT
16 tháng 11 2023
a) 1/4(x-3)+2=1/5
1/4.(x-3) = 1/5-2
1/4.(x-3) = -9/5
x-3 = (-9/5):1/4
x-3 = -36/5
x = -36/5+3
x= -21/5
11 tháng 8 2023
2:
a: =4+3/8+5+2/3
=9+3/8+2/3
=216/24+9/24+16/24
=216/24+25/24
=241/24
b; =2+3/8+1+1/4+3+6/7
=6+3/8+1/4+6/7
=6+5/8+6/7
=419/56
c: \(=2+\dfrac{3}{8}-1-\dfrac{1}{4}+5+\dfrac{1}{3}\)
=6+3/8-1/4+1/3
=6+1/8+1/3
=6+11/24
=155/24
d: \(=3+\dfrac{5}{6}+6\cdot\dfrac{13}{6}\)
=3+13+5/6
=16+5/6
=101/6
e: =3+1/2+4+5/7-5-5/14
=3+4-5+1/2+5/7-5/14
=2+7/14+10/14-5/14
=2+12/14
=2+6/7=20/7
f: =9/2+1/2:11/2
=9/2+1/11
=99/22+2/22=101/22
11 tháng 8 2023
2:
a: =4+3/8+5+2/3
=9+3/8+2/3
=216/24+9/24+16/24
=216/24+25/24
=241/24
b; =2+3/8+1+1/4+3+6/7
=6+3/8+1/4+6/7
=6+5/8+6/7
=419/56
c: \(=2+\dfrac{3}{8}-1-\dfrac{1}{4}+5+\dfrac{1}{3}\)
=6+3/8-1/4+1/3
=6+1/8+1/3
=6+11/24
=155/24
d: \(=3+\dfrac{5}{6}+6\cdot\dfrac{13}{6}\)
=3+13+5/6
=16+5/6
=101/6
e: =3+1/2+4+5/7-5-5/14
=3+4-5+1/2+5/7-5/14
=2+7/14+10/14-5/14
=2+12/14
=2+6/7=20/7
f: =9/2+1/2:11/2
=9/2+1/11
=99/22+2/22=101/22
JS
26 tháng 3 2020
a. \(\left[\left(-2\right)^5.2014-4^2.2015\right]-\left(-2015^0+3^2-2^3\right)\)
\(=-64448-32240+1-9+8=-96688\)
27 tháng 3 2020
Tớ lm lại nhé:
SBC = 9-1/2-1/3-1/4-...-1/10
=1+1+...+1(9 số 1) -1/2-1/3-1/4-1/5-...-1/10.
=(1-1/2)+(1-1/3)+...+(1-1/10)
=1/2+2/3+...+9/10= SC
=> phép chia có thương là 1(vì SBC=SC)
26 tháng 6 2023
15: A= 1/3-3/4+3/5+1/2007-1/36+1/15-2/9
Sửa đề:
A=-3/4-2/9-1/36+1/3+3/5+1/15+1/2007
=-27/36-8/36-1/36+5/15+9/15+1/15+1/2007
=-1+1+1/2007=1/2007
16:
\(A=\dfrac{1}{3}+\dfrac{3}{5}+\dfrac{1}{15}-\dfrac{3}{4}-\dfrac{2}{9}-\dfrac{1}{36}+\dfrac{1}{64}\)
\(=\dfrac{5+9+1}{15}+\dfrac{-27-8-1}{36}+\dfrac{1}{64}\)
=1/64
17:
=1/2-1/2+2/3-2/3+3/4-3/4+4/5-4/5+5/6-5/6-6/7
=-6/7
17 tháng 8 2023
1:
a: =23/27-11/17+4/27+28/17
=23/27+4/27+28/17-11/17
=1+1=2
b: \(=\dfrac{2}{3}\cdot\left(\dfrac{7}{9}+\dfrac{2}{9}\right)-\dfrac{2}{9}\)
=2/3-2/9
=6/9-2/9
=4/9
c: \(=\dfrac{11}{5}\cdot\dfrac{7}{3}-\dfrac{1}{3}\cdot\dfrac{11}{5}\)
=11/5(7/3-1/3)
=11/5*2
=22/5
d: \(=\dfrac{3}{2}\cdot\dfrac{4}{3}\cdot...\cdot\dfrac{2024}{2023}=\dfrac{2024}{2}=1012\)
e: \(=\dfrac{1}{2}\cdot\dfrac{2}{3}\cdot...\cdot\dfrac{2022}{2023}=\dfrac{1}{2023}\)
NK
1
20 tháng 8 2023
A= 1+ \(\dfrac{1}{2}\) (1+2) + \(\dfrac{1}{3}\) (1+2+3)+.....+
\(\dfrac{1}{9}\) (1+2+3+....+9)
=1+ \(\dfrac{1}{2}\) ×2×3 + \(\dfrac{1}{3}\) × \(\dfrac{3×4}{2}\)+.....+
\(\dfrac{1}{9}\) × \(\dfrac{9×10}{2}\)
= 1+\(\dfrac{3}{2}\) + \(\dfrac{4}{2}\)+....+
\(\dfrac{10}{2}\)
=\(\dfrac{2}{2}\) + \(\dfrac{3}{2}\) + \(\dfrac{4}{2}\) +......+
\(\dfrac{10}{2}\)
=\(\dfrac{2+3+4+...10}{2}\)
=\(\dfrac{12×10}{2}{2}\)
= \(\dfrac{12×10}{4}\)
= 12×5 = tự nhân ra
Vậy A bằng ở trên .
Nhớ tích mình nhé:)
A = \(\dfrac{1}{1+2}\) + \(\dfrac{1}{1+2+3}\) +...+ \(\dfrac{1}{1+2+3+...+9}\)
A = \(\dfrac{1}{\left(2+1\right)\times2:2}\)+ \(\dfrac{1}{\left(1+3\right)\times3:2}\)+...+ \(\dfrac{1}{\left(1+9\right)\times9:2}\)
A = \(\dfrac{2}{2\times\left(1+2\right)}\)+ \(\dfrac{2}{3\times\left(1+4\right)}\)+...+ \(\dfrac{2}{9\times\left(1+9\right)}\)
A = \(\dfrac{2}{2\times3}\) + \(\dfrac{2}{3\times4}\)+....+ \(\dfrac{2}{9\times10}\)
A = 2 \(\times\)( \(\dfrac{1}{2\times3}\) + \(\dfrac{1}{3\times4}\)+...+ \(\dfrac{1}{9\times10}\))
A = 2 \(\times\) ( \(\dfrac{1}{2}\) - \(\dfrac{1}{3}\) + \(\dfrac{1}{3}\) - \(\dfrac{1}{4}\)+...+ \(\dfrac{1}{9}\) - \(\dfrac{1}{10}\))
A = 2 \(\times\)( \(\dfrac{1}{2}\) - \(\dfrac{1}{10}\))
A = 2 \(\times\) \(\dfrac{2}{5}\)
A = \(\dfrac{4}{5}\)