tính
a10+5=???
b 12+ 3=???
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a: \(=\dfrac{-5}{8}+\dfrac{7}{12}=\dfrac{-15}{24}+\dfrac{14}{24}=\dfrac{-1}{24}\)
b: \(=\dfrac{3}{4}-\dfrac{5}{6}+\dfrac{11}{12}=\dfrac{9}{12}-\dfrac{10}{12}+\dfrac{11}{12}=\dfrac{10}{12}=\dfrac{5}{6}\)
c: \(=\dfrac{6}{36}-\dfrac{1}{36}=\dfrac{5}{36}\)
d: \(=\dfrac{5}{12}+\dfrac{5}{12}=\dfrac{10}{12}=\dfrac{5}{6}\)
e: \(=\dfrac{-8}{56}-\dfrac{7}{56}=\dfrac{-15}{56}\)
f: \(=\dfrac{-5}{15}+\dfrac{3}{25}=\dfrac{-25}{75}+\dfrac{9}{75}=\dfrac{-16}{75}\)
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\(A=2+2^2+2^3+...+2^{2016}\)
\(\Rightarrow2A=2\left(2+2^2+2^3+...+2^{2016}\right)\)
\(\Rightarrow2A=2^2+2^3+2^4+...+2^{2017}\)
\(\Rightarrow2A-A=2^2+2^3+...+2^{2017}-2-2^2-2^3-...-2^{2016}\)
\(\Rightarrow A=2^{2017}-2\)
\(B=12+12^2+12^3+...+12^{100}\)
\(\Rightarrow12B=12\left(12+12^2+12^3+12^{100}\right)\)
\(\Rightarrow12B=12^2+12^3+...+12^{101}\)
\(\Rightarrow12B-B=12^2+12^3+...+12^{101}-12-12^2-12^3-...-12^{100}\)
\(\Rightarrow11B=12^{101}-12\)
\(\Rightarrow B=\dfrac{12^{101}-12}{11}\)
\(C=5+5^2+5^3+...+5^{32}\)
\(\Rightarrow5C=5\left(5+5^2+...+5^{32}\right)\)
\(\Rightarrow5C=5^2+5^3+...+5^{33}\)
\(\Rightarrow5C-C=5^2+5^3+...+5^{33}-5-5^2-...-5^{32}\)
\(\Rightarrow4C=5^{33}-5\)
\(\Rightarrow C=\dfrac{5^{33}-5}{4}\)
a) \(A=2+2^2+2^3+...+2^{2016}\)
\(2A=2^2+2^3+2^4+...+2^{2017}\)
\(\Rightarrow2A-A=\left(2^2+2^3+2^4+...+2^{2017}\right)-\left(2+2^2+2^3+...+2^{2017}\right)\)
\(\Rightarrow A=\left(2^2+2^3+2^4+...+2^{2016}\right)+2^{2017}-2-\left(2^2+2^3+2^4+...+2^{2016}\right)\)
\(\Rightarrow A=2^{2017}-2\)
Vậy \(A=2^{2017}-2\)
a) - { - 7 - [ - (- 5) +23 ] - [ - 9 - (- 7) - (- 23) ] + 5 }
=- { - 7 - ( 5 +23 ) - ( - 9 + 7 + 23) + 5 }
=-(-7-28-21+5)
=-(-51)
=51
b) 12 - { [ - 9 + (-17) - (-3) ] + [ - 3 + (-9 ) - (- 3) ] - 12 - (- 3) }
= 12 - { [ - 9 + (-17) +3) ] + [ - 3 + (-9 ) +3) ] - 12 + 3 }
=12-[ (-23)+(-9)-9 ]
=12-(-41)
=12+41
=53
a) \(\dfrac{3}{4}-\dfrac{1}{8}=\dfrac{6}{8}-\dfrac{1}{8}=\dfrac{6-1}{8}=\dfrac{5}{8}\)
b) \(\dfrac{2}{6}-\dfrac{5}{18}=\dfrac{6}{18}-\dfrac{5}{18}=\dfrac{6-5}{18}=\dfrac{1}{18}\)
c) \(\dfrac{2}{5}-\dfrac{3}{20}=\dfrac{8}{20}-\dfrac{3}{20}=\dfrac{8-3}{20}=\dfrac{5}{20}=\dfrac{1}{4}\)
a: \(=\left[-15+2013-36\right]:\left(-2\right)-1+27\)
\(=\dfrac{1962}{-2}+26\)
\(=-981+26=-955\)
b: \(=\dfrac{-35}{-7}+\left(-12\right)-\left(-1\right)=5+1-12=-6\)
c: \(=-2^9\cdot\left(-2\right)^5+6^2-1-\left(-125\right)\)
\(=2^{14}+36-1+125\)
\(=16384+36+124=16544\)
a: \(=3\sqrt{3}-2\sqrt{3}+4\sqrt{3}-5\sqrt{3}=2\sqrt{3}\)
10+5=15
12+3=15
a, 10 + 5 = 15
b, 12 + 3 = 15