Tính :
\(A=\left(12^2+14^2+...+20^2\right)-\left(1^2+3^2+5^2+7^2+9^2\right)\)
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Tính M
M=\(\left(12^2+14^2+16^2+18^2+20^2\right)-\left(1^2+3^2+5^2+7^2+9^2\right)\)\(9^{2\left(\right)}\)
Tính:Aleft(1-frac{2}{3}+frac{4}{3}right)-left(frac{4}{5}-1right)+left(frac{7}{5}+2right)Bleft(-3+frac{3}{4}-frac{1}{3}right):left(5+frac{2}{5}-frac{2}{3}right)Cleft(frac{3}{5}-frac{4}{15}right).left(frac{2}{7}-frac{3}{14}right)-left(frac{5}{9}-frac{7}{27}right).left(1-frac{3}{5}right)+left(1-frac{11}{12}right).left(1+frac{11}{12}right)Dfrac{left(frac{3}{10}-frac{4}{15}-frac{7}{20}right).frac{-5}{19}}{left(frac{1}{14}+frac{1}{7}-frac{-3}{35}right).frac{4}{3}}
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Tính:
A=\(\left(1-\frac{2}{3}+\frac{4}{3}\right)-\left(\frac{4}{5}-1\right)+\left(\frac{7}{5}+2\right)\)
B=\(\left(-3+\frac{3}{4}-\frac{1}{3}\right):\left(5+\frac{2}{5}-\frac{2}{3}\right)\)
C=\(\left(\frac{3}{5}-\frac{4}{15}\right).\left(\frac{2}{7}-\frac{3}{14}\right)-\left(\frac{5}{9}-\frac{7}{27}\right)\)\(.\left(1-\frac{3}{5}\right)+\left(1-\frac{11}{12}\right).\left(1+\frac{11}{12}\right)\)
D=\(\frac{\left(\frac{3}{10}-\frac{4}{15}-\frac{7}{20}\right).\frac{-5}{19}}{\left(\frac{1}{14}+\frac{1}{7}-\frac{-3}{35}\right).\frac{4}{3}}\)
Cho biết : \(1^2+2^2+3^2+...+10^2=385.\)Tính nhanh : \(\left(12^2+14^2+16^2+18^2+20^2\right)-\left(1^2+3^2+5^2+7^2+9^2\right)\)
Cho : \(1^2+2^2+3^2+.....+10^2=385\)
Tính S= \(\left(12^2+14^2+16^2+18^2+20^2\right)-\left(1^2+3^2+5^2+7^2+9^2\right)\)
Ta thấy : 2\(^2\)=4=4.1\(^2\)
4\(^2\)=16=4.2\(^2\)
6\(^2\)=36=4.3\(^2\)
...
20\(^2\)=400=4.10\(^2\)
=>S=2\(^2\)+4\(^2\)+6\(^2\)+...+20\(^2\)=4.(1\(^2\)+2\(^2\)+3\(^2\)+...+10\(^2\))
= 4.385
=1540
Vậy tổng S = 1540
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Cho \(1^2+2^2+3^2+...+10^2=385\)
Tính nhanh S = \(\left(12^2+14^2+16^2+18^2+20^2\right)-\left(1^2+3^2+5^2+7^2+9^2\right)\)
1155 nhé bn nhưng mk k bt cách làm
Bn nào bt giúp mk vs
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Cho biết \(1^2+2^2+3^2+....+10^2=365\)
Tính nhanh S= \(\left(12^2+14^2+16^2+18^2+20^2\right)-\left(1^2+3^2+5^2+7^2+9^2\right)\)
1, Tính
\(A=\left(-3+\frac{3}{4}-\frac{1}{3}\right):\left(5+\frac{2}{5}-\frac{2}{3}\right)\)
\(B=\left(\frac{3}{5}-\frac{4}{15}\right).\left(\frac{2}{7}-\frac{3}{14}\right)-\left(\frac{5}{9}-\frac{7}{27}\right).\left(1-\frac{3}{5}\right)+\left(1-\frac{11}{12}\right).\left(1+\frac{11}{12}\right)\)
A=\(-\frac{155}{284}\)
B=\(-\frac{43}{3780}\)
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Tính : A left(1-frac{2}{3}+frac{4}{3}right)-left(frac{4}{5}-1right)+left(frac{7}{5}+2right)B left(-3+frac{3}{4}-frac{1}{3}right):left(5+frac{2}{5}-frac{2}{3}right)C left(frac{3}{5}-frac{4}{5}right).left(frac{2}{7}-frac{3}{14}right)-left(frac{5}{9}-frac{7}{27}right).left(1-frac{3}{5}right)+left(1-frac{11}{12}right).left(1-frac{11}{12}right)
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Tính :
A = \(\left(1-\frac{2}{3}+\frac{4}{3}\right)-\left(\frac{4}{5}-1\right)+\left(\frac{7}{5}+2\right)\)
B = \(\left(-3+\frac{3}{4}-\frac{1}{3}\right):\left(5+\frac{2}{5}-\frac{2}{3}\right)\)
C = \(\left(\frac{3}{5}-\frac{4}{5}\right).\left(\frac{2}{7}-\frac{3}{14}\right)-\left(\frac{5}{9}-\frac{7}{27}\right).\left(1-\frac{3}{5}\right)+\left(1-\frac{11}{12}\right).\left(1-\frac{11}{12}\right)\)
A = (1 - 2/3 + 4/3) - (4/5 - 1) + (7/5 + 2)
A= (3/3 - 2/3 + 4/3) - (4/5 - 5/5) + (7/5 + 10/5)
A= 5/3 + 1/5 + 17/5
A= 5/3 +18/5
A= 25/15 + 54/15
A= 79/15
B= (-3 + 3/4 - 1/3 ) : (5 + 2/5 - 2/3)
B= (-36/12 + 9/12 - 4/12) : (75/15 + 6/15 - 10/15)
B= -31/12 : 71/15
B= -155/284
C= (3/5 - 4/5 ) . (2/7 - 3/14) - (5/9 - 7/27) . (1 - 3/5) + (1 - 11/12) . (1-11/12)
C= -1/5 . 1/14 - 8/27 . 2/5 + 1/12 . 1/12
C=-1/70 - 16/135 + 1/144
C=-216/15120 - 1792/15120 + 105/15120
C=-1903/15120
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Cho biết \(1^2+2^2+3^2+...+10^2=385\).Tính nhanh : \(\left(12^2+14^2+16^2+18^2+20^2\right)-\left(1^2+3^2+5^5+7^2+9^2\right)\)
\(A=\left(12^2+14^2+16^2+18^2+20^2\right)-\left(1^2+3^2+5^2+7^2+9^2\right)\)
\(A=\left(12^2-1^2\right)+\left(14^2-3^2\right)+\left(16^2-5^2\right)+\left(18^2-7^2\right)+\left(20^2-9^2\right)\)\(A=\left(12+1\right)\left(12-1\right)+\left(14+3\right)\left(14-3\right)+\left(16-5\right)\left(16+5\right)+\left(18-7\right)\left(18+7\right)+\left(20-9\right)\left(20+9\right)\)
\(A=11.13+11.17+11.21+11.25+11.29\)
\(A=11.\left(13+17+21+25+29\right)\)
\(A=11.\left[\left(13+17\right)+\left(21+29\right)+25\right]\)
\(A=11.\left(30+50+25\right)\)
\(A=11.105=1155\)
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