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a)\(\sqrt{1}\)+\(\sqrt{9}\)+\(\sqrt{25}\)+\(\sqrt{49}\)+\(\sqrt{81}\)
=1+3+5+7+9
=25
b)=\(\dfrac{1}{2}\)+\(\dfrac{1}{3}\)+\(\dfrac{1}{6}\)+\(\dfrac{1}{4}\)
=\(\dfrac{6}{12}\)+\(\dfrac{4}{12}\)+\(\dfrac{2}{12}\)+\(\dfrac{3}{12}\)
=\(\dfrac{15}{12}\)
c) =0,2+0.3+0,4
= 0.9
d) =9-8+7
=8
j) =1,2-1,3+1.4
= (-0,1)+1,4
=1,4
g) \(\dfrac{2}{5}\)+\(\dfrac{5}{2}\)+\(\dfrac{9}{10}\)+\(\dfrac{3}{4}\)
= (\(\dfrac{4}{10}\)+\(\dfrac{15}{10}\)+\(\dfrac{9}{10}\))+\(\dfrac{3}{4}\)
= \(\dfrac{14}{5}\)+\(\dfrac{3}{4}\)
=\(\dfrac{56}{20}\)+\(\dfrac{15}{20}\)
= \(\dfrac{71}{20}\)
Nhớ tick cho mk nha~
a: \(=0.5\cdot10-\dfrac{1}{7}+15=20-\dfrac{1}{7}=\dfrac{139}{7}\)
b: \(=6\cdot\dfrac{-2}{3}+12\cdot\dfrac{4}{9}+18\cdot\dfrac{-8}{27}\)
\(=-4+\dfrac{16}{3}-\dfrac{16}{3}=-4\)
c: \(=\left(\dfrac{5}{2}+\dfrac{3}{8}-\dfrac{5}{8}+\dfrac{2}{3}\right):\left(\dfrac{17}{2}+\dfrac{49}{4}-\dfrac{17}{8}+\dfrac{34}{15}\right)\)
\(=\dfrac{35}{12}:\dfrac{2507}{120}=\dfrac{350}{2507}\)
a) \(A=\dfrac{1}{\sqrt{25}}+\dfrac{\sqrt{49}}{\sqrt{36}}-\dfrac{2}{\sqrt{100}}.\)
\(=\dfrac{1}{5}+\dfrac{7}{6}-\dfrac{1}{5}.\)
\(=\left(\dfrac{1}{5}-\dfrac{1}{5}\right)+\dfrac{7}{6}.\)
\(=0+\dfrac{7}{6}=\dfrac{7}{6}.\)
Vậy \(A=\dfrac{7}{6}.\)
b) \(B=\sqrt{\dfrac{0,01}{1,21}}+3.\dfrac{2}{\sqrt{10^2}+2^2+40}-\dfrac{3}{4}.\)
\(=\dfrac{1}{11}+3.\dfrac{2}{10+4+40}-\dfrac{3}{4}.\)
\(=\dfrac{1}{11}+3.\dfrac{1}{37}-\dfrac{3}{4}.\)
\(=\dfrac{1}{11}+\dfrac{1}{9}-\dfrac{3}{4}.\)
\(=\dfrac{36}{396}+\dfrac{44}{396}-\dfrac{297}{296}.\)
\(=-\dfrac{217}{396}.\)
Vậy \(B=-\dfrac{217}{396}.\)
\(=10.\dfrac{1}{10}.\dfrac{4}{3}+3.7-\dfrac{1}{6}.2\)
\(=1.\dfrac{4}{3}+21+\dfrac{1}{3}\)
\(=\dfrac{4}{3}+21+\dfrac{1}{3}\)
\(=\dfrac{28}{21}+\dfrac{441}{21}+\dfrac{7}{21}\)
\(=\dfrac{469}{21}+\dfrac{7}{21}\)
\(=\dfrac{68}{3}\)
\(10.\sqrt{0,01}.\sqrt{\dfrac{16}{9}}+3.\sqrt{49}-\dfrac{1}{6}.\sqrt{4}\)
= 10 . 0,1 . \(\dfrac{4}{3}\) + 3. 7 - \(\dfrac{1}{6}.2\)
= 1 . \(\dfrac{4}{3}\) + 21 - \(\dfrac{1}{3}\)
= \(\dfrac{4}{3}+21-\dfrac{1}{3}\)
= 22
\(linh=\dfrac{1}{\sqrt{1}}+\dfrac{1}{\sqrt{2}}+\dfrac{1}{\sqrt{3}}+....+\dfrac{1}{\sqrt{99}}+\dfrac{1}{\sqrt{100}}\)
\(\left\{{}\begin{matrix}\dfrac{1}{\sqrt{1}}>\dfrac{1}{\sqrt{100}}\\\dfrac{1}{\sqrt{2}}>\dfrac{1}{\sqrt{100}}\\.............\\\dfrac{1}{\sqrt{99}}>\dfrac{1}{\sqrt{100}}\end{matrix}\right.\)
Suy ra:
\(\dfrac{1}{\sqrt{1}}+\dfrac{1}{\sqrt{2}}+....+\dfrac{1}{\sqrt{99}}>\dfrac{1}{\sqrt{100}}+\dfrac{1}{\sqrt{100}}+...+\dfrac{1}{\sqrt{100}}\)
\(\Leftrightarrow\dfrac{1}{\sqrt{1}}+\dfrac{1}{\sqrt{2}}+...+\dfrac{1}{\sqrt{99}}>\dfrac{99}{\sqrt{100}}\)
\(linh=\dfrac{1}{\sqrt{1}}+\dfrac{1}{\sqrt{2}}+.....+\dfrac{1}{\sqrt{99}}+\dfrac{1}{\sqrt{100}}>\dfrac{99}{\sqrt{100}}+\dfrac{1}{\sqrt{100}}\)
\(\)\(linh>10\left(đpcm\right)\)
Bài này ko phải 100 nhé
1.
0,2 . \(\sqrt{100}\) - \(\sqrt{\dfrac{16}{25}}\)
= 0,2 . 10 - \(\dfrac{4}{5}\)
= 2 - \(\dfrac{4}{5}\)
= \(\dfrac{6}{5}\)
1/ \(0,2.\sqrt{100}-\sqrt{\dfrac{16}{25}}\)
\(=0,2.10-0,8\)
\(=2-0,8=1,2\)
2/ \(\dfrac{2^7.9^3}{6^5.8^2}\)
\(=\dfrac{93312}{497664}=\dfrac{3}{16}=0,1875\)
3/ \(\sqrt{0,01}-\sqrt{0,25}\)
\(=0,1-0,5\)
\(=-0,4\)
4/ \(0,5.\sqrt{100}-\sqrt{\dfrac{1}{4}}\)
\(=0,5.10-0,5\)
\(=5-0,5=4,5\)
5/ \(7.\sqrt{0,01}+2.\sqrt{0,25}\)
\(=7.0,1+2.0,5\)
\(=0,7+1=1,7\)
6/ \(0,5.\sqrt{100}-\sqrt{\dfrac{1}{25}}\)
\(=0,5.10-0,2\)
\(=5-0,2=4,8\)
Tính:
C = \(3\dfrac{1}{2}.\dfrac{4}{49}-\left[2,\left(4\right).2\dfrac{5}{11}\right]:\left(\dfrac{-42}{5}\right)\)
= \(\dfrac{7}{2}.\dfrac{4}{49}-\left[\left(2+0,\left(1\right).4\right).\dfrac{27}{5}\right].\dfrac{-5}{42}\)
= \(\dfrac{1.2}{1.7}-\left[\left(2+\dfrac{1.4}{9}\right).\dfrac{27}{5}\right].\dfrac{-5}{42}\)
= \(\dfrac{2}{7}-\left[\dfrac{18+4}{9}.\dfrac{27}{5}\right].\dfrac{-5}{42}\)
= \(\dfrac{2}{7}-\left[\dfrac{22.9}{3.5}\right].\dfrac{-5}{42}\)
= \(\dfrac{2}{7}-\dfrac{198}{15}.\dfrac{-5}{42}=\dfrac{2}{7}-\dfrac{11}{3}.\dfrac{-1}{7}\)
= \(\dfrac{2}{7}+\dfrac{11}{21}\) = \(\dfrac{6+11}{21}\) = \(\dfrac{17}{21}\)
\(\sqrt{9=3}\)
\(\sqrt{25=5}\)
\(\sqrt{49=7}\)
\(\sqrt{100=10}\)
Ta có :
\(\dfrac{1}{\sqrt{1}}>\dfrac{1}{\sqrt{100}}=\dfrac{1}{10}\)
\(\dfrac{1}{\sqrt{2}}>\dfrac{1}{\sqrt{100}}=\dfrac{1}{10}\)
.............................
\(\dfrac{1}{\sqrt{99}}>\dfrac{1}{\sqrt{100}}=\dfrac{1}{10}\)
\(\dfrac{1}{\sqrt{100}}=\dfrac{1}{\sqrt{100}}=\dfrac{1}{10}\)
\(\Leftrightarrow\dfrac{1}{\sqrt{1}}+\dfrac{1}{\sqrt{2}}+.........+\dfrac{1}{\sqrt{99}}+\dfrac{1}{\sqrt{100}}>\dfrac{1}{10}+\dfrac{1}{10}+.....+\dfrac{1}{10}=\dfrac{100}{10}=10\)
\(\Leftrightarrow\dfrac{1}{\sqrt{1}}+\dfrac{1}{\sqrt{2}}+......+\dfrac{1}{\sqrt{100}}>10\left(đpcm\right)\)
a\\(\sqrt{49}+\sqrt{4}=7+2=9\)
b\\(\sqrt{0,25}-\sqrt{0.01}=0.5-01=0.4\)
c\\(\sqrt{\dfrac{16}{25}}-\sqrt{\dfrac{1}{81}}=\dfrac{4}{5}-\dfrac{1}{9}=\dfrac{31}{45}\)
d\\(\sqrt{64}-\sqrt{16}+\sqrt{\left(-3\right)^2}=8-4+3=7\)
e\\(2-\sqrt{0,36}=2-0.6=1.4\)
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Trả lời:
\(\sqrt{\dfrac{49}{100}}=\sqrt{\dfrac{7}{10}}\)
\(\sqrt{\dfrac{49}{100}}=\dfrac{7}{10}\)