Tính hợp lý
C= 9. (-1/3)3 + 1/3
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\(\dfrac{-2}{9}-\dfrac{3}{4}+\dfrac{3}{5}+\dfrac{1}{15}+\dfrac{1}{57}+\dfrac{1}{3}-\dfrac{1}{36}\)
\(=\left(-\dfrac{2}{9}-\dfrac{3}{4}-\dfrac{1}{36}\right)+\left(\dfrac{3}{5}+\dfrac{1}{15}+\dfrac{1}{3}\right)+\dfrac{1}{57}\)
\(=\dfrac{-8-27-1}{36}+\dfrac{9+1+5}{15}+\dfrac{1}{57}\)
\(=-\dfrac{36}{36}+\dfrac{15}{15}+\dfrac{1}{57}\)
\(=\dfrac{1}{57}\)
\(A=\dfrac{-1}{9}+\dfrac{3}{9}+\dfrac{3}{7}+\dfrac{6}{7}=\dfrac{2}{9}+\dfrac{9}{7}=\dfrac{14+81}{63}=\dfrac{95}{63}\)
1: =5/8*17/13*7/17*8/3*6
=5/3*7/13*6
=5*7*2/13=70/13
2: =-7/9(24/19-1)
=-7/9*5/19
=-35/171
3: =-3/8(7/6-9/6)
=-3/8*(-2/6)
=3/8*1/3=1/8
Bài 1:
\(A=\dfrac{-1}{3}+1+\dfrac{1}{3}=1\)
\(B=\dfrac{2}{15}+\dfrac{5}{9}-\dfrac{6}{9}=\dfrac{2}{15}-\dfrac{1}{9}=\dfrac{18-15}{135}=\dfrac{3}{135}=\dfrac{1}{45}\)
\(C=\dfrac{-1}{5}+\dfrac{1}{4}-\dfrac{3}{4}=\dfrac{-1}{5}-\dfrac{1}{2}=\dfrac{-7}{10}\)
Bài 2:
a: \(=\dfrac{1}{5}+\dfrac{1}{2}+\dfrac{2}{5}-\dfrac{3}{5}+\dfrac{2}{21}-\dfrac{10}{21}+\dfrac{3}{20}\)
\(=\left(\dfrac{1}{5}+\dfrac{2}{5}-\dfrac{3}{5}\right)+\left(\dfrac{2}{21}-\dfrac{10}{21}\right)+\left(\dfrac{1}{2}+\dfrac{3}{20}\right)\)
\(=\dfrac{-8}{21}+\dfrac{13}{20}=\dfrac{113}{420}\)
b: \(B=\dfrac{21}{23}-\dfrac{21}{23}+\dfrac{125}{93}-\dfrac{125}{143}=\dfrac{6250}{13299}\)
Bài 3:
\(\dfrac{7}{3}-\dfrac{1}{2}-\left(-\dfrac{3}{70}\right)=\dfrac{7}{3}-\dfrac{1}{2}+\dfrac{3}{70}=\dfrac{490}{210}-\dfrac{105}{210}+\dfrac{9}{210}=\dfrac{394}{210}=\dfrac{197}{105}\)
\(\dfrac{5}{12}-\dfrac{3}{-16}+\dfrac{3}{4}=\dfrac{5}{12}+\dfrac{3}{16}+\dfrac{3}{4}=\dfrac{20}{48}+\dfrac{9}{48}+\dfrac{36}{48}=\dfrac{65}{48}\)
Bài 4:
\(\dfrac{3}{4}-x=1\)
\(\Rightarrow-x=1-\dfrac{3}{4}\)
\(\Rightarrow x=-\dfrac{1}{4}\)
Vậy: \(x=-\dfrac{1}{4}\)
\(x+4=\dfrac{1}{5}\)
\(\Rightarrow x=\dfrac{1}{5}-4\)
\(\Rightarrow x=-\dfrac{19}{5}\)
Vậy: \(x=-\dfrac{19}{5}\)
\(x-\dfrac{1}{5}=2\)
\(\Rightarrow x=2+\dfrac{1}{5}\)
\(\Rightarrow x=\dfrac{11}{5}\)
Vậy: \(x=\dfrac{11}{5}\)
\(x+\dfrac{5}{3}=\dfrac{1}{81}\)
\(\Rightarrow x=\dfrac{1}{81}-\dfrac{5}{3}\)
\(\Rightarrow x=-\dfrac{134}{81}\)
Vậy: \(x=-\dfrac{134}{81}\)
a) \(\left(6-\frac{2}{3}+\frac{1}{2}\right)-\left(5+\frac{5}{3}-\frac{3}{2}\right)-\left(3-\frac{7}{3}+\frac{5}{2}\right)\)
\(=6-\frac{2}{3}+\frac{1}{2}-5-\frac{5}{3}+\frac{3}{2}-3+\frac{7}{3}-\frac{5}{2}\)
\(=\left(-\frac{2}{3}-\frac{5}{3}+\frac{7}{3}\right)+\left(\frac{1}{2}+\frac{3}{2}-\frac{5}{2}\right)+\left(6-5-3\right)\)
\(=0+2-\frac{5}{2}+\left(-2\right)=\left(2-2\right)-\frac{5}{2}=0-\frac{5}{2}=-\frac{5}{2}\)
Bài làm
\(\frac{1}{3}+\frac{3}{4}-\left(-\frac{3}{5}\right)+\frac{1}{72}+\frac{2}{9}-\left(-\frac{1}{36}\right)+\frac{1}{15}\)
\(=\frac{1}{3}+\frac{3}{4}+\frac{3}{5}+\frac{1}{72}+\frac{2}{9}+\frac{1}{36}+\frac{1}{15}\)
\(=\left(\frac{1}{3}+\frac{3}{5}+\frac{1}{15}\right)+\left(\frac{1}{36}+\frac{3}{4}\right)+\left(\frac{1}{72}+\frac{2}{9}\right)\)
\(=\left(\frac{5}{15}+\frac{9}{15}+\frac{1}{15}\right)+\left(\frac{1}{36}+\frac{27}{36}\right)+\left(\frac{16}{72}+\frac{1}{72}\right)\)
\(=1+\frac{28}{36}+\frac{18}{72}\)
\(=\frac{36}{36}+\frac{28}{36}+\frac{9}{36}\)
\(=\frac{73}{36}\)
~ Không chắc có đúng hay không nx. ~
# Học tốt #
Sửa đề :
\(\frac{1}{3}+\frac{3}{4}-\left[-\frac{3}{5}\right]+\frac{1}{72}+\frac{2}{9}-\frac{1}{36}+\frac{1}{15}\)
\(=\frac{1}{3}+\frac{3}{4}+\frac{3}{5}+\frac{1}{72}+\frac{2}{9}-\frac{1}{36}+\frac{1}{15}\)
\(=\left[\frac{1}{3}+\frac{3}{5}+\frac{1}{15}\right]-\left[\frac{3}{4}+\frac{2}{9}+\frac{1}{36}\right]+\frac{1}{72}\)
\(=\left[\frac{5}{15}+\frac{9}{15}+\frac{1}{15}\right]-\left[\frac{27}{36}+\frac{8}{36}+\frac{1}{36}\right]+\frac{1}{72}\)
\(=1-1+\frac{1}{72}=\frac{1}{72}\)
C= 9. (-1/3)3 + 1/3
C= 9. -1/27+1/3
C= -1/3+1/3
C= 0
Khó quá bn ak