2010+2015x2016/2018x2015-2020
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Những câu hỏi liên quan
SR
1
GS
1
LL
3
8 tháng 8 2018
21 + 22 + 23 + ... + 2100
Ta có : S = 2 + 22 + 23 + ... + 2100
2S = 2.(2 + 22 + 23 + ... + 2100)
2S = 22 + 23 + ... + 2100 + 2101
2S - S = (22 + 23 + ... + 2100 + 2101) - (2 + 22 + 23 + ... + 2100)
S = 2101 - 2
8 tháng 8 2018
\(2^1+2^2+2^3+...+2^{100}\)
Ta có : \(S=2+2^2+2^3+....2^{100}\)
: \(2S=2.\left(2+2^2+2^3+....+2^{100}\right)\)
: \(2S=2^2+2^3+.....+2^{100}+2^{101}\)
: \(2S-S=\left(2^2+2^3+....+2^{100}+2^{101}\right)\)\(-\left(2+2^2+2^3+.....+2^{100}\right)\)
: \(S=2^{101}-2\)
BT
28 tháng 4 2018
<=> 10x-9,9=0,1.x+9,9
<=> 100x-99=x+99
<=> 99x=99+99
<=> 99x=198 => x=198:99 => x=2
Đáp số: x=2
XA
3
18 tháng 8 2021
\(d,\dfrac{5}{7}+\dfrac{9}{23}+-\dfrac{12}{7}+\dfrac{14}{23}\)
\(=\left(\dfrac{5}{7}+\dfrac{-12}{7}\right)+\left(\dfrac{9}{23}+\dfrac{14}{23}\right)\)
\(=-\dfrac{7}{7}+\dfrac{23}{23}\)
\(=\left(-1\right)+1=0\)
\(e,\dfrac{3}{17}+-\dfrac{5}{13}+-\dfrac{18}{35}+\dfrac{14}{17}+\dfrac{17}{-35}+-\dfrac{8}{13}\)
\(=\left(\dfrac{3}{17}+\dfrac{14}{17}\right)+\left(\dfrac{-5}{13}+\dfrac{-8}{13}\right)+\left(\dfrac{-18}{35}+\dfrac{-17}{35}\right)\)
\(=\dfrac{17}{17}+\dfrac{-13}{13}+-\dfrac{35}{35}\)
\(=1+\left(-1\right)+\left(-1\right)=0+\left(-1\right)=-1\)
\(f,\dfrac{-3}{8}. \dfrac{1}{6}+\dfrac{3}{-8}.\dfrac{5}{6}+\dfrac{-10}{16}\)
\(=\dfrac{-3}{8}.\dfrac{1}{6}+\dfrac{-3}{8}.\dfrac{5}{6}+\dfrac{-10}{16}\)
\(=\dfrac{-3}{8}.\left(\dfrac{1}{6}+\dfrac{5}{6}\right)+-\dfrac{10}{16}\)
=\(\dfrac{-3}{8}.1+\dfrac{-10}{16}\)
\(=\dfrac{-3}{8}+\dfrac{-10}{16}\)
\(=\dfrac{-6}{16}+\dfrac{-10}{16}=\dfrac{-16}{16}=-1\)
\(g,\dfrac{-4}{11}.\dfrac{5}{15}.\dfrac{11}{-4}=\dfrac{-4}{11}.\dfrac{5}{15}.\dfrac{-11}{4}\)
\(=\left(\dfrac{-4}{11}.\dfrac{-11}{4}\right).\dfrac{5}{15}\)
\(=1.\dfrac{5}{15}=1.\dfrac{1}{3}=\dfrac{1}{3}\)
\(h,\dfrac{7}{36}-\dfrac{8}{-9}+\dfrac{-2}{3}=\dfrac{7}{36}-\dfrac{-8}{9}+\dfrac{-2}{3}\)
\(=\dfrac{7}{36}-\dfrac{-32}{36}+\dfrac{-24}{36}=\dfrac{7-\left(-32\right)+\left(-24\right)}{36}\)
\(=\dfrac{15}{56}=\dfrac{5}{12}\)
Tick mình nha ^^
18 tháng 8 2021
d.\(\dfrac{5}{7}\)+\(\dfrac{9}{23}\)+\(\dfrac{12}{7}\)+\(\dfrac{14}{23}\)=(\(\dfrac{5}{7}\)+\(\dfrac{12}{7}\))+(\(\dfrac{9}{23}\)+\(\dfrac{14}{23}\))
=\(\dfrac{17}{7}\)+ 1 = \(\dfrac{24}{7}\)
e.\(\dfrac{3}{17}\)+\(\dfrac{-5}{13}\)+\(\dfrac{-18}{35}\)+\(\dfrac{14}{17}\)+\(\dfrac{17}{-35}\)+\(\dfrac{-8}{13}\)
=(\(\dfrac{3}{17}\)+\(\dfrac{14}{17}\))+(\(\dfrac{-5}{13}\)+\(\dfrac{-8}{13}\))+(\(\dfrac{-18}{35}\)+\(\dfrac{17}{-35}\))
= 1+ (-1) + (-1) = -1
f. \(\dfrac{-3}{8}\).\(\dfrac{1}{6}\)+\(\dfrac{3}{-8}\).\(\dfrac{5}{6}\)+\(\dfrac{-10}{16}\)=\(\dfrac{-3}{8}\)(\(\dfrac{1}{6}\)+\(\dfrac{5}{6}\)) + \(\dfrac{-5}{8}\)
=\(\dfrac{-3}{8}\)+\(\dfrac{-5}{8}\)= -1
g. \(\dfrac{-4}{11}\).\(\dfrac{5}{15}\).\(\dfrac{11}{-4}\)=\(\dfrac{5}{15}\)
h.\(\dfrac{7}{36}\)-\(\dfrac{8}{-9}\)+\(\dfrac{-2}{3}\)= \(\dfrac{7}{36}\)-\(\dfrac{-32}{36}\)+\(\dfrac{-24}{36}\)
=\(\dfrac{-49}{36}\)
13 tháng 9 2015
\(2009^{2010}+2009^{2009}=2009^{2009}.2009+2009^{2009}=2009^{2009}.\left(2009+1\right)=2009.2010\)\(2010^{2010}=2010.2010^{2009}\)
Dễ thấy \(2009^{2009}.2010
XA
2
21 tháng 8 2021
a. x : 13/16 = 5/-8
x : 13/16 = -5/8
x = -5/8 . 13/16
x = -65/128
21 tháng 8 2021
b.
x . \(\dfrac{-14}{28}\) = \(\dfrac{6}{-9}\) - \(\dfrac{2}{15}\)
x . \(\dfrac{-14}{28}\) = \(\dfrac{-9}{6}\) - \(\dfrac{2}{15}\)
x . \(\dfrac{-14}{28}\) = \(\dfrac{-49}{30}\)
x = \(\dfrac{-49}{30}\) : \(\dfrac{-14}{28}\)
x = \(\dfrac{-49}{30}\) . \(\dfrac{-28}{14}\)
x = \(\dfrac{-49}{15}\)
Bạn thử bỏ tất cả chữ số không đi xem nào
Ví dụ: 21+215x216/218x215-22
2010+2015x2016/2018x2015-2020
=2010+2015x2016/(2016+2)x2015-2020
=2010+2015x2016/2016x2015+4030-2020
=2010+2015x2016/2016x2015+2010
=1
k mình nha ?