Tính
D=1+5+5^5+5^9+...+5^28
K
Khách
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TA
25 tháng 6 2023
d) \(\sqrt{46+6\sqrt{5}}=\sqrt{45+2\cdot3\sqrt{5}+1}=\sqrt{\left(3\sqrt{5}\right)^2+2\cdot3\sqrt{5}+1}=\sqrt{\left(3\sqrt{5}+1\right)^2}=\left|3\sqrt{5}+1\right|=3\sqrt{5}+1\)
e) \(\sqrt{9+4\sqrt{2}}=\sqrt{8+2\cdot2\sqrt{2}+1}=\sqrt{\left(2\sqrt{2}\right)^2+2\cdot2\sqrt{2}+1}=\sqrt{\left(2\sqrt{2}+1\right)^2}=\left|2\sqrt{2}+1\right|=2\sqrt{2}+1\)
f) \(\sqrt{16+2\sqrt{15}}=\sqrt{15+2\sqrt{15}+1}=\sqrt{\left(\sqrt{15}+1\right)^2}=\left|\sqrt{15}+1\right|=\sqrt{15}+1\)
GH
25 tháng 6 2023
d
\(=\sqrt{45+\sqrt{180}+1}=\sqrt{45+\sqrt{36.5}+1}=\sqrt{45+6\sqrt{5}+1}\\ =\sqrt{\left(\sqrt{45}\right)^2+6\sqrt{5}+1}=\sqrt{\left(\sqrt{45}+1\right)^2}=\sqrt{45}+1\)
e
\(=\sqrt{8+\sqrt{32}+1}=\sqrt{8+\sqrt{4.8}+1}=\sqrt{\left(\sqrt{8}\right)^2+2\sqrt{8}+1^2}=\sqrt{\left(\sqrt{8}+1\right)^2}=\sqrt{8}+1\)
f
\(\sqrt{15+2\sqrt{15}+1}=\sqrt{\left(\sqrt{15}+1\right)^2}=\sqrt{15}+1\)
PH
0
19 tháng 1 2022
4: \(=\dfrac{2+3}{7}+\dfrac{1+6}{9}-\dfrac{5}{6}=\dfrac{5}{7}+\dfrac{7}{9}-\dfrac{5}{6}=\dfrac{83}{126}\)
5: \(=\dfrac{-5-2}{7}+\dfrac{3+1}{4}-\dfrac{1}{5}=-\dfrac{1}{5}\)
6: \(=\dfrac{-3-28}{31}+\dfrac{-6-1}{17}+\dfrac{1-5}{25}=-1-\dfrac{7}{17}-\dfrac{4}{25}=-\dfrac{668}{425}\)
TM
19 tháng 1 2022
4. \(\dfrac{2}{7}+\dfrac{1}{9}+\dfrac{3}{7}+\dfrac{5}{9}+\dfrac{-5}{6}\)
\(=\left(\dfrac{2}{7}+\dfrac{3}{7}\right)+\left(\dfrac{1}{9}+\dfrac{5}{9}\right)+\dfrac{-5}{6}\)
\(=\dfrac{5}{7}+\dfrac{2}{3}+\dfrac{-5}{6}\)
\(=\dfrac{30+28+\left(-35\right)}{42}=\dfrac{23}{42}\)
5. \(\dfrac{-5}{7}+\dfrac{3}{4}+\dfrac{-1}{5}+\dfrac{-2}{7}+\dfrac{1}{4}\)
\(=\left(\dfrac{-5}{7}+\dfrac{-2}{7}\right)+\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\dfrac{-1}{5}\)
\(=\dfrac{-7}{7}+\dfrac{4}{4}+\dfrac{-1}{5}\)
\(=-1+1+\dfrac{-1}{5}\)
\(=-\dfrac{1}{5}\)
6. \(\dfrac{-3}{31}+\dfrac{-6}{17}+\dfrac{1}{25}+\dfrac{-28}{31}+\dfrac{-1}{17}+\dfrac{-1}{5}\)
\(=\left(\dfrac{-3}{31}+\dfrac{-28}{31}\right)+\left(\dfrac{-6}{17}+\dfrac{-1}{17}\right)+\dfrac{1}{25}+\dfrac{-1}{5}\)
\(=\dfrac{-31}{31}+\dfrac{-7}{17}+\dfrac{1}{25}+\dfrac{-1}{5}\)
\(=-1+\dfrac{-7}{17}+\dfrac{1}{25}+\dfrac{-1}{5}\)
\(=\dfrac{-425+\left(-175\right)+17+\left(-85\right)}{425}=\dfrac{-668}{425}\)
29 tháng 7 2018
A) 7/38 x 9/11 +7/38 x 4/11 -7/38 x 2/11
=7/38.(9/11+4/11-2/11)
=7/38
B) 5/31 x 21/25 + 5/31 x -7/10 - 5/31 x 9/20
=5/31.(21/25-7/10-9/20)
=5/31.(-31/100)
=-1/20
H9
HT.Phong (9A5)
CTVHS
9 tháng 8 2023
B1:
\(13956-8768=5188\)
\(4368:78=56\)
\(4512:96=47\)
\(1665:45=37\)
9 tháng 8 2023
3:
\(A=2\left(\dfrac{2}{5\cdot7}+\dfrac{2}{7\cdot9}+...+\dfrac{2}{53\cdot55}\right)\)
=2(1/5-1/7+1/7-1/9+...+1/53-1/55)
=2(1/5-1/55)
=2*10/55
=2*2/11
=4/11
8 tháng 6 2020
Bài làm
a) \(\left(\frac{3}{8}+\frac{-1}{4}+\frac{5}{12}\right):\frac{2}{3}\)
\(=\left(\frac{9}{24}+\frac{-6}{24}+\frac{10}{24}\right).\frac{3}{2}\)
\(=\frac{13}{24}.\frac{3}{2}\)
\(=\frac{39}{48}\)
b) \(\frac{-5}{7}.\frac{2}{11}+\frac{-5}{7}.\frac{9}{11}+1\frac{5}{7}\)
\(=-\frac{5}{7}.\left(\frac{2}{11}+\frac{9}{11}\right)+\frac{12}{7}\)
\(=-\frac{5}{7}.1+\frac{12}{7}\)
\(=\frac{7}{7}\)
\(=1\)
c) \(0,25:\left(10,3-9,8\right)-\frac{3}{4}\)
\(=\frac{25}{100}:\left(0,5\right)-\frac{3}{4}\)
\(=\frac{5}{4}:\frac{1}{2}-\frac{3}{4}\)
\(=\frac{5}{4}.2-\frac{3}{4}\)
\(=\frac{5}{2}-\frac{3}{4}\)
\(=\frac{10}{4}-\frac{3}{4}=\frac{7}{4}\)
d) \(-\frac{5}{9}.\frac{13}{28}-\frac{13}{28}.\frac{4}{9}\)
\(=-\frac{13}{28}\left(\frac{5}{9}+\frac{4}{9}\right)\)
\(=-\frac{13}{28}.\frac{9}{9}\)
\(=-\frac{13}{28}.1\)
\(=-\frac{13}{28}\)
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