Chứng minh rằng:
\(\dfrac{1}{4}\)+\(\dfrac{1}{11}\)+\(\dfrac{1}{18}\)+
\(\dfrac{1}{21}\)+\(\dfrac{1}{24}\)+\(\dfrac{1}{27}\)+\(\dfrac{1}{29}\) < \(\dfrac{4}{5}\)
\(\dfrac{help}{me}\)
Những câu hỏi liên quan
12 tháng 7 2023 lúc 19:40
Tínha.dfrac{4}{9}+dfrac{3}{7} dfrac{3}{4}+dfrac{7}{24} dfrac{1}{3}+dfrac{2}{9}+dfrac{4}{27}b.dfrac{5}{6}-dfrac{3}{8} dfrac{7}{15}-dfrac{11}{30} dfrac{2}{3}+dfrac{1}{6}-dfrac{7}{12}c.dfrac{18}{25}timesdfrac{15}{6} dfrac{30}{49}:dfrac{6}{7} dfrac{1}{2}timesdfrac{3}{4}:dfrac{6}{5}d.8timesdfrac{3}{5}:dfrac{12}{5} 4:dfrac{9}{5}:dfrac{10}{3}3 bn đầu tiên xong mik sẽ tick
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Tính
a.\(\dfrac{4}{9}+\dfrac{3}{7}\) \(\dfrac{3}{4}+\dfrac{7}{24}\) \(\dfrac{1}{3}+\dfrac{2}{9}+\dfrac{4}{27}\)
b.\(\dfrac{5}{6}-\dfrac{3}{8}\) \(\dfrac{7}{15}-\dfrac{11}{30}\) \(\dfrac{2}{3}+\dfrac{1}{6}-\dfrac{7}{12}\)
c.\(\dfrac{18}{25}\times\dfrac{15}{6}\) \(\dfrac{30}{49}:\dfrac{6}{7}\) \(\dfrac{1}{2}\times\dfrac{3}{4}:\dfrac{6}{5}\)
d.\(8\times\dfrac{3}{5}:\dfrac{12}{5}\) \(4:\dfrac{9}{5}:\dfrac{10}{3}\)
3 bn đầu tiên xong mik sẽ tick
a: 4/9+3/7=28/63+27/63=55/63
3/4+7/24=18/24+7/24=25/24
1/3+2/9+4/27=9/27+6/27+4/27=19/27
b: 5/6-3/8=20/24-9/24=11/24
7/15-11/30=14/30-11/30=3/30=1/10
2/3+1/6-7/12
=8/12+2/12-7/12
=3/12=1/4
c: 18/25*15/6=15/25*18/6=3*3/5=9/5
30/49:6/7=30/49*7/6=210/294=5/7
1/2*3/4:6/5=3/8*5/6=15/48=5/16
d: 8*3/5:12/5=24/5*5/12=2
4:9/5:10/3=4*5/9*3/10=2/3
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Chứng minh rằng: \(\dfrac{1}{1\cdot2}+\dfrac{1}{3\cdot4}+\dfrac{1}{5\cdot6}+...+\dfrac{1}{49\cdot50}=\dfrac{1}{26}+\dfrac{1}{27}+\dfrac{1}{28}+...+\dfrac{1}{50}\)
help mik với
Ta có:
1/1.2 + 1/3.4 + 1/5.6 + ... + 1/49.50 = 1/26 + 1/27 + 1/28 + .. + 1/50
Xét vế trái:
1/1.2 + 1/3.4 + 1/5.6 + ... + 1/49.50
= 1 - 1/2 + 1/3 - 1/4 + 1/5 - 1/6 + ... + 1/49 - 1/50
= ( 1 + 1/3 + 1/5 + ... + 1/49 ) - ( 1/2 + 1/4 + 1/6 + ... + 1/50 )
= ( 1 + 1/3 + 1/5 + ... + 1/49 ) + (1/2 + 1/4 + 1/6 + ... + 1/50 ) - 2 . ( 1/2 + 1/4 + 1/6 + ... + 1/50 )
= ( 1 + 1/2 + 1/3 + 1/4 + ...+ 1/49 + 1/50 ) - ( 1 + 1/2 + 1/3 + ... + 1/25 )
= 1/26 + 1/27 + 1/28 + ... + 1/49 + 1/50 (1)
Từ (1) => Vế trái = Vế phải
=> Điều phải chứng minh
- HokTot -
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\(\dfrac{29-x}{21}\)+\(\dfrac{27-x}{23}\)+\(\dfrac{25-x}{25}\)+\(\dfrac{23-x}{27}\)+\(\dfrac{21-x}{29}\)=\(\dfrac{(29-x+1}{21}\)+\(\dfrac{(27-x+1)}{23}\)+\(\dfrac{(25-x+1)}{25}\)+\(\dfrac{(23-x+1)}{21}\)=-5 +5
GIẢI nốt hộ mình với ạ
Chứng minh rằng : \(\dfrac{1}{1+a^4}+\dfrac{1}{1+b^4}+\dfrac{1}{1+c^4}\ge\dfrac{1}{1+ab^3}+\dfrac{1}{1+bc^3}+\dfrac{1}{1+ca^3}\)
HELP ME!!!
tính
a)\(\dfrac{-10}{11}.\dfrac{8}{9}+\dfrac{7}{18}.\dfrac{10}{11}\)
b)\(\dfrac{3}{14}:\dfrac{1}{28}-\dfrac{13}{21}:\dfrac{1}{28}+\dfrac{29}{42}:\dfrac{1}{28}-8\)
c)\(-1\dfrac{5}{7}.15+\dfrac{2}{7}\left(-15\right)+\left(-105\right).\left(\dfrac{2}{3}-\dfrac{4}{5}+\dfrac{1}{7}\right)\)
ăn lồn cái địt mẹ mày lửa trùa ĐẦU LỒN nhá
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Xem thêm câu trả lời
Bài 1:
a, Tính \(\dfrac{5.4^{15}.9^{9} - 4.3^{20}.8^{9}}{5.2^{9}.6^{19}-7.2^{29}.27^{6}}\)
b,Tìm x biết:
\(1\dfrac{1}{30}:(24\dfrac{1}{6}-24\dfrac{1}{5}) -\dfrac{1\dfrac{1}{2}-\dfrac{3}{4}}{4x-\dfrac{1}{2}}=(-1\dfrac{1}{15}):(8\dfrac{1}{5}-8\dfrac{1}{3})\)
Bài 2: Chứng minh số:
222...22200333...333(2001c/s 2; 2003 c/s3)
Cho a ,c > 0 và ab > 1. Chứng minh rằng : \(\dfrac{1}{1+a^4}+\dfrac{1}{1+b^4}+\dfrac{1}{1+c^4}\ge\dfrac{1}{1+ab^3}+\dfrac{1}{1+bc^3}+\dfrac{1}{ca^3}\)
HELP ME!!!!!
20 tháng 12 2021 lúc 22:10
a, 1dfrac{5}{18}+dfrac{7}{25}-dfrac{5}{18}+dfrac{18}{25}-0, 75b, dfrac{2}{5}.dfrac{1}{3}-dfrac{4}{3}.dfrac{2}{5}c, (dfrac{-1}{4}).( 6dfrac{2}{11}) + 3 dfrac{9}{11}.(dfrac{-1}{4})d, 4. (-dfrac{1}{2})^{3_{ }}-_{ }2. (dfrac{-1}{2})^2 + 3. (dfrac{-1}{2}) + 1e, dfrac{1}{6}-(dfrac{2}{3})^2 + dfrac{5}{18}f, (dfrac{4}{3}-dfrac{3}{2})^2- 2.|-dfrac{1}{9}| + (-dfrac{5}{18})
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a, 1\(\dfrac{5}{18}\)+\(\dfrac{7}{25}\)-\(\dfrac{5}{18}\)+\(\dfrac{18}{25}\)-0, 75
b, \(\dfrac{2}{5}\).\(\dfrac{1}{3}\)-\(\dfrac{4}{3}\).\(\dfrac{2}{5}\)
c, (\(\dfrac{-1}{4}\)).( 6\(\dfrac{2}{11}\)) + 3 \(\dfrac{9}{11}\).(\(\dfrac{-1}{4}\))
d, 4. (-\(\dfrac{1}{2}\))\(^{3_{ }}\)-\(_{ }\)2. (\(\dfrac{-1}{2}\))\(^2\) + 3. (\(\dfrac{-1}{2}\)) + 1
e, \(\dfrac{1}{6}\)-(\(\dfrac{2}{3}\))\(^2\) + \(\dfrac{5}{18}\)
f, (\(\dfrac{4}{3}\)-\(\dfrac{3}{2}\))\(^2\)- 2.|-\(\dfrac{1}{9}\)| + (-\(\dfrac{5}{18}\))
e: \(=\dfrac{1}{6}-\dfrac{4}{9}+\dfrac{5}{18}=\dfrac{3-8+5}{18}=0\)
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tính một cách hợp lí:
a) \(\dfrac{-5}{18}+\dfrac{32}{45}-\dfrac{9}{10}\)
b) \(\left(\dfrac{-1}{4}+\dfrac{51}{33}-\dfrac{5}{3}\right)-\left(\dfrac{-15}{12}+\dfrac{6}{11}-\dfrac{42}{29}\right)\)
c) \(1-\dfrac{1}{2}+2-\dfrac{2}{3}+3-\dfrac{3}{4}+4-\dfrac{1}{4}-3-\dfrac{1}{3}-2-\dfrac{1}{2}-1\)
giải chi tiết giúp mình nha
a) Ta có: \(\dfrac{-5}{18}+\dfrac{32}{45}-\dfrac{9}{10}\)
\(=\dfrac{-25}{90}+\dfrac{64}{90}-\dfrac{81}{90}\)
\(=\dfrac{-42}{90}=-\dfrac{7}{15}\)
b) Ta có: \(\left(-\dfrac{1}{4}+\dfrac{51}{33}-\dfrac{5}{3}\right)-\left(-\dfrac{15}{12}+\dfrac{6}{11}-\dfrac{42}{29}\right)\)
\(=\dfrac{-1}{4}+\dfrac{17}{11}-\dfrac{5}{3}+\dfrac{5}{4}-\dfrac{6}{11}+\dfrac{42}{29}\)
\(=\dfrac{-5}{3}+\dfrac{42}{29}\)
\(=\dfrac{-145}{87}+\dfrac{126}{87}=\dfrac{-19}{87}\)
c) Ta có: \(1-\dfrac{1}{2}+2-\dfrac{2}{3}+3-\dfrac{3}{4}+4-\dfrac{1}{4}-3-\dfrac{1}{3}-2-\dfrac{1}{2}-1\)
\(=\left(1-1\right)-\left(\dfrac{1}{2}+\dfrac{1}{2}\right)+\left(2-2\right)-\left(\dfrac{2}{3}+\dfrac{1}{3}\right)+\left(3-3\right)-\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+4\)
\(=-1-1-1+4\)
=1
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a) Ta có: =−2590+6490−8190=−2590+6490−8190
(−14+5133−53)−(−1512+611−4229)(−14+5133−53)−(−1512+611−4229)
=−53+4229=−53+4229
1−12+2−23+3−34+4−14−3−13−2−12−11−12+2−23+3−34+4−14−3−13−2−12−1
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