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f) \(2\cdot5^2+3:71^0-54:3^3\)
\(=2\cdot25+3:1-54:27\)
\(=50+3-2\)
\(=51\)
h) \(5\cdot3^2-32:4^2\)
\(=5\cdot9-32:16\)
\(=45-2\)
\(=43\)
k) \(5^6:5^4+2^3\cdot2^2-1^{2017}\)
\(=5^2+2^5-1\)
\(=25+32-1\)
\(=56\)
n) \(23\cdot75+5^2\cdot10+5^2\cdot13+180\)
\(=23\cdot25\cdot3+25\cdot10+25\cdot13+180\)
\(=25\cdot\left(23\cdot3+10+13\right)+180\)
\(=25\cdot92+180\)
\(=2300+180\)
\(=2480\)
f: =2*25+3-54:27
=50+3-2
=51
h: =5*9-32:16
=45-2=43
k: =5^2+2^5-1
=25+32-1
=25+31=56
n: =23*75+25*23+180
=2300+180
=2480
a) 0,(1) + 0,(13) - 0,(123)
=0,(24)-0,(123)
=0,(119301)
b) 4,(14) + 2,(133)
\(\approx6,2745\)
a) Mình ko ghi lại đề nhé!
= \(\frac{1}{2}\) - ( \(\frac{1}{3.7}\) + \(\frac{1}{7.11}\) + ... + \(\frac{1}{23.27}\) )
= \(\frac{1}{2}\) - \(\frac{1}{4}\) . ( \(\frac{1}{3}\) - \(\frac{1}{7}\) + \(\frac{1}{7}\) - .... - \(\frac{1}{27}\) )
= \(\frac{1}{2}\) - \(\frac{1}{4}\) . ( \(\frac{1}{3}\) - \(\frac{1}{27}\) )
= \(\frac{1}{2}\) - \(\frac{1}{4}\) . \(\frac{8}{27}\)
= \(\frac{1}{2}\) - \(\frac{2}{27}\) = \(\frac{23}{54}\)
b) ..............................................................................
= \(\frac{1}{5}\) . ( \(\frac{5}{5.10}\) - \(\frac{5}{10.15}\) - ... - \(\frac{5}{95.100}\) )
= \(\frac{1}{5}\) . ( \(\frac{1}{5}\) - \(\frac{1}{10}\) + \(\frac{1}{10}\) - ... - \(\frac{1}{100}\) )
= \(\frac{1}{5}\) . ( \(\frac{1}{5}\) - \(\frac{1}{100}\) )
= \(\frac{1}{5}\) . \(\frac{19}{100}\)
= \(\frac{19}{500}\)
k mình nha! Chúc bạn học tốt và được nhiều k!
Sử dụng hằng đẳng thức: \(x^3-y^3=\left(x-y\right)\left(x^2+xy+y\right)\)và \(x^3+y^3=\left(x+y\right)\left(x^2-xy+y^2\right)\)
Lưu ý: \(\left(x\pm y\right)=x^2\pm2xy+y^2\)
a, 5\(\dfrac{4}{27}\) + \(\dfrac{6}{23}\) + 0,25 - \(\dfrac{4}{27}\) + \(\dfrac{17}{23}\)
= 5 + (\(\dfrac{4}{27}\) - \(\dfrac{4}{27}\)) + (\(\dfrac{6}{23}\) + \(\dfrac{17}{23}\)) + 0,25
= 5 + 1 + 0,25
= 6,25
b, 16.(\(\dfrac{1}{2}\))3 - \(\dfrac{3}{5}\): 0,75
= 16.\(\dfrac{1}{8}\) - 0,8
= 2 - 0,8
= 1,2