\(25.\left(\frac{-1^3}{5}\right):\left(\frac{1}{4}-0,75^2\right)\)

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23 tháng 10 2016

25.-1/125 :(1/4-27/64)

=25.-1/125:(16/64+ -27/64)

=25. -1/125:-11/64

=25.64/1375

=64/55

23 tháng 10 2016

NẾU ĐÚNG THÌ NHỚ TÍCH CHO MÌNH NHÉ

Bài 1:

a) Ta có: \(25\cdot\left(\frac{-1}{5}\right)^3+\frac{1}{5}-2\cdot\left(\frac{-1}{2}\right)^2-\frac{1}{2}\)

\(=25\cdot\frac{-1}{125}+\frac{1}{5}-2\cdot\frac{1}{4}-\frac{1}{2}\)

\(=-\frac{1}{5}+\frac{1}{5}-\frac{1}{2}-\frac{1}{2}\)

\(=\frac{-2}{2}=-1\)

b) Ta có: \(35\frac{1}{6}:\left(\frac{-4}{5}\right)-46\frac{1}{6}:\left(\frac{-4}{5}\right)\)

\(=\frac{211}{6}\cdot\frac{-5}{4}-\frac{277}{6}\cdot\frac{-5}{4}\)

\(=\frac{-5}{4}\cdot\left(\frac{211}{6}-\frac{277}{6}\right)\)

\(=\frac{-5}{4}\cdot\left(-11\right)=\frac{55}{4}\)

c) Ta có: \(\left(\frac{-3}{4}+\frac{2}{5}\right):\frac{3}{7}+\left(\frac{3}{5}+\frac{-1}{4}\right):\frac{3}{7}\)

\(=\frac{-7}{20}\cdot\frac{7}{3}+\frac{7}{20}\cdot\frac{7}{3}\)

\(=\frac{7}{3}\cdot\left(-\frac{7}{20}+\frac{7}{20}\right)=\frac{7}{3}\cdot0=0\)

d) Ta có: \(\frac{7}{8}:\left(\frac{2}{9}-\frac{1}{18}\right)+\frac{7}{8}\cdot\left(\frac{1}{36}-\frac{5}{12}\right)\)

\(=\frac{7}{8}\cdot6+\frac{7}{8}\cdot\frac{-7}{18}\)

\(=\frac{7}{8}\cdot\left(6+\frac{-7}{18}\right)\)

\(=\frac{7}{8}\cdot\frac{101}{18}=\frac{707}{144}\)

e) Ta có: \(\frac{1}{6}+\frac{5}{6}\cdot\frac{3}{2}-\frac{3}{2}+1\)

\(=\frac{1}{6}+\frac{15}{12}-\frac{3}{2}+1\)

\(=\frac{2}{12}+\frac{15}{12}-\frac{18}{12}+\frac{12}{12}\)

\(=\frac{11}{12}\)

f) Ta có: \(\left(-0,75-\frac{1}{4}\right):\left(-5\right)+\frac{1}{15}-\left(-\frac{1}{5}\right):\left(-3\right)\)

\(=\left(-1\right):\left(-5\right)+\frac{1}{15}-\frac{1}{15}\)

\(=\frac{1}{5}\)

14 tháng 9 2016

a) \(\left(-5\right)^2\).\(\left(-5\right)^3\) = -3125

22 tháng 2 2020

C = \(25.\left(\frac{-1}{3}\right)^3\) \(+\frac{1}{5}\) \(-2.\left(\frac{-1}{2}\right)^2\) \(-\frac{1}{2}\)

C = \(25.\left(\frac{-1}{27}\right)+\frac{1}{5}\) \(-2.\frac{1}{4}\) \(-\frac{1}{2}\)

C = \(\frac{-25}{27}\) \(+\frac{1}{5}\) \(-\frac{1}{2}\) \(-\frac{1}{2}\)

C = \(\frac{-25}{27}\) \(+\frac{1}{5}\) \(-1\)

C = \(\frac{-125}{135}\) \(+\frac{27}{135}\) \(-\frac{135}{135}\)

C = \(\frac{-233}{135}\)

D =  \(-8.\left(\frac{3}{4}-\frac{1}{4}\right):\left(\frac{9}{4}-\frac{7}{6}\right)\)

D = \(-8.\frac{1}{2}\) \(.\frac{12}{13}\)

D = \(-4.\frac{12}{13}\)

D = \(\frac{-48}{13}\)

E = \(5\sqrt{16}\) \(-4\sqrt{9}\) \(+\sqrt{25}\) \(-0,3\sqrt{400}\)

E = \(5.4-4.3+5-0,3.20\)

E = \(20-12+5-6\)

E = \(8+\left(-1\right)\)

E = \(7\)

F = \(\left(\frac{-3}{2}\right)\) \(+\left|\frac{-5}{6}\right|\) \(-1\frac{1}{2}\) \(:6\)

F = \(\left(\frac{-3}{2}\right)\) \(+\frac{5}{6}\) \(-\frac{3}{2}\) \(.\frac{1}{6}\)

F = \(\left(\frac{-3}{2}\right)\) \(+\frac{5}{6}\) \(-\frac{1}{4}\) 

F = \(\left(\frac{-18}{12}\right)\) \(+\frac{10}{12}\) \(-\frac{3}{12}\)

F = \(\frac{-11}{12}\)

 Chúc cậu hk tốt ~ 

c)  C = ( 1 - 2 ) + ( 3 - 4 ) + ... + ( 79 - 80 )

     C = ( -1 ) + ( -1 ) + ... + ( -1 )

     C = ( -1 ) x ( 80 - 1 + 1 ) : 2

     C = ( -1 ) x 80 : 2

     C = ( -40 )

4 tháng 7 2017

C=1-2+3-4+...+79-80

=(1-2)+(3-4)+...+(79-80)

=-1+(-1)+...+(-1) (có 80 số hạng bàng -1)

=-1*80

=-80