25+(-8)+(-25)+(-2)-(-2)
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\(\left(25-11^2\right)\left(25-10^2\right)\left(25-9^2\right)...\left(25-5^2\right)\left(25-4^2\right)\left(25-3^2\right)\left(25-2^2\right)\left(25-1^2\right)\)
\(=\left(25-11^2\right)\left(25-10^2\right)\left(25-9^2\right)...\left(25-25\right)\left(25-4^2\right)\left(25-3^2\right)\left(25-2^2\right)\left(25-1^2\right)\)
\(=\left(25-11^2\right)\left(25-10^2\right)\left(25-9^2\right)...0.\left(25-4^2\right)\left(25-3^2\right)\left(25-2^2\right)\left(25-1^2\right)\)
\(=0\)
![](https://rs.olm.vn/images/avt/0.png?1311)
\(\left(25-11^2\right)\left(25-10^2\right)\left(25-9^2\right)...\left(25-5^2\right)\left(25-4^2\right)\left(25-3^2\right)\left(25-2^2\right)\left(25-1^2\right)\)
\(=\left(25-11^2\right)\left(25-10^2\right)\left(25-9^2\right)...\left(25-25\right)\left(25-4^2\right)\left(25-3^2\right)\left(25-2^2\right)\left(25-1^2\right)\)
\(=\left(25-11^2\right)\left(25-10^2\right)\left(25-9^2\right)....0.\left(25-4^2\right)\left(25-3^2\right)\left(25-2^2\right)\left(25-1^2\right)\)
\(=0\)
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\(A=\dfrac{9}{8}-\dfrac{8}{9}+\dfrac{3}{24}+\dfrac{1}{4}-\dfrac{5}{16}+\dfrac{19}{25}-\dfrac{1}{9}+\dfrac{2}{25}-\dfrac{1}{81}\)
\(=\dfrac{9}{8}+\dfrac{1}{4}-\dfrac{5}{16}+\dfrac{1}{8}-\dfrac{8}{9}-\dfrac{1}{9}-\dfrac{1}{81}+\dfrac{19}{25}+\dfrac{2}{25}\)
\(=\dfrac{10}{8}+\dfrac{1}{4}-\dfrac{5}{16}-1-\dfrac{1}{81}+\dfrac{21}{25}\)
\(=\dfrac{20+4-5}{16}-\dfrac{82}{81}+\dfrac{21}{25}\)
\(=\dfrac{19}{16}-\dfrac{82}{81}+\dfrac{21}{25}\)
\(=\dfrac{32891}{16\cdot81\cdot25}\)
b: \(B=-\dfrac{1}{3}-\dfrac{8}{35}-\dfrac{2}{9}-\dfrac{1}{35}+\dfrac{4}{5}-\dfrac{4}{9}+\dfrac{3}{7}\)
\(=\dfrac{-1}{3}-\dfrac{2}{9}-\dfrac{4}{9}-\dfrac{8}{35}-\dfrac{1}{35}+\dfrac{4}{5}+\dfrac{3}{7}\)
\(=\dfrac{-3-2-4}{9}+\dfrac{-9}{35}+\dfrac{28+15}{35}\)
\(=-1+\dfrac{-9+43}{35}=-1+\dfrac{34}{35}=-\dfrac{1}{35}\)
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a, 410. 230=220.230=250
b,925.274.813= 350.312.312=374
Tương tự các câu khác....
a, 410.230 = (22)10.230 = 220.230 = 250
b, 925.274.813 = (32)25.(33)4.(34)3 = 350.312.312 = 374
c, 2550.1255 = (52)50.(53)5 = 5100.515 = 5115
d, 643.48.164 = (26)3.(22)8.(24)4 = 218.216.216 = 250
e, 38 : 36 = 32
210 : 83 = 210 : (23)3 = 210 : 29 = 2
127 : 67 = (12 : 6)7 = 27
@Dương Tuyết Mai
\(25+\left(-8\right)+\left(-25\right)+\left(-2\right)-\left(-2\right)\)
\(=\left(25-25\right)+\left(-8\right)+\left(-2+2\right)\)
\(=0-8+0\)
\(=-8\)