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Cách 1 :
\(A=\left(6-\frac{2}{3}+\frac{1}{2}\right)-\left(5+\frac{5}{3}-\frac{3}{2}\right)-\left(3-\frac{7}{3}+\frac{5}{2}\right)\)
\(=\frac{35}{6}-\frac{31}{6}-\frac{19}{6}\)
\(=\frac{35-31-19}{6}=-\frac{5}{2}\)
Cách 2 :
\(A=\left(6-\frac{2}{3}+\frac{1}{2}\right)-\left(5+\frac{5}{3}-\frac{3}{2}\right)-\left(3-\frac{7}{3}+\frac{5}{2}\right)\)
\(=6-\frac{2}{3}+\frac{1}{2}-5-\frac{5}{3}+\frac{3}{2}-3+\frac{7}{3}-\frac{5}{2}\)
\(=\left(6-5-3\right)+\left(-\frac{2}{3}-\frac{5}{3}+\frac{7}{3}\right)+\left(\frac{1}{2}+\frac{3}{2}-\frac{5}{2}\right)\)
\(=\left(-2\right)+0+\left(-\frac{1}{2}\right)=-\frac{5}{2}\)
\(A=\frac{99}{100}-\left(\frac{1}{1.2}+\frac{1}{2.3}+..+\frac{1}{99.100}\right)\)
\(A=\frac{99}{100}-\left(1-\frac{1}{100}\right)\)
\(A=\frac{99}{100}-\frac{99}{100}\)
\(A=\frac{99-99}{100}=0\)
Bài 2
\(\left(3x+5\right).\left(2x-4\right)=0\)
\(TH1:3x+5=0\)
\(3x=-5\)
\(x=-\frac{5}{3}\)
\(TH2:2x-4=0\)
\(2x=4\)
\(x=2\)
\(\left(x^2-1\right).\left(x+3\right)=0\)
\(\Rightarrow x^2-1=0\)
\(x^2=1\)
\(\Rightarrow x=1\)
\(x+3=0\)
\(x=-3\)
\(5x^2-\frac{1}{2}x=0\)
\(\Rightarrow5x^2-\frac{x}{2}=0\)
\(\Rightarrow5x^2=\frac{5x^2}{1}=\frac{5x^2.2}{2}\)
\(10x^2-x=x.\left(10x-1\right)\)
\(\frac{x.\left(10x-1\right)}{2}=0\)
\(\frac{x.\left(10x-1\right)}{2}.2=0.2\)
\(10x-1=0\)
\(x=\frac{1}{10}=0.100\)
\(\Rightarrow\orbr{\begin{cases}x=\frac{1}{10}=0.100\\x=0\end{cases}}\)
\(\frac{x}{4}-\frac{1}{2}=\frac{3}{4}\)
\(\frac{x}{4}=\frac{3}{4}+\frac{1}{2}\)
\(\frac{x}{4}=\frac{5}{4}\)
\(\Rightarrow x=5\)
\(\frac{1}{8}+\frac{7}{8}:x=\frac{3}{4}\)
\(\frac{7}{8}:x=\frac{3}{4}-\frac{1}{8}\)
\(x=\frac{7}{8}:\frac{5}{8}\)
\(x=\frac{56}{40}=\frac{28}{20}=\frac{14}{10}=\frac{7}{5}\)
\(2:\left(\frac{1}{2}-\frac{2}{3}\right)^3=2:\left(-\frac{1}{6}\right)^3=2:\left(-\frac{1}{216}\right)=-432\)
\(\frac{5^4}{25^5}\cdot\frac{20^4}{4^5}=\frac{5^4\cdot20^4}{25^5\cdot4^5}=\frac{5^4\cdot4^4\cdot5^4}{5^5\cdot5^5\cdot4^5}=\frac{1}{100}\)
~CÁC BẠN GIÚP MK LÊN 200 ĐIỂM NHA. BẠN NÀO GIÚP THÌ MK K LẠI NHÉ.~
~THANKS~
Cách 1 :
\(A=\left(6-\frac{2}{3}+\frac{1}{2}\right)-\left(5+\frac{5}{3}-\frac{3}{2}\right)-\left(3-\frac{7}{3}+\frac{5}{2}\right)\)
\(\Rightarrow A=6-\frac{2}{3}+\frac{1}{2}-5-\frac{5}{3}+\frac{3}{2}-3+\frac{7}{3}-\frac{5}{2}\)
\(\Rightarrow A=\left(6-5-3\right)+\left(\frac{7}{3}-\frac{2}{3}-\frac{5}{3}\right)+\left(\frac{1}{2}+\frac{3}{2}-\frac{5}{2}\right)\)
\(\Rightarrow A=-2+0+-\frac{1}{2}\)
\(\Rightarrow A=-2+\frac{-1}{2}\)
\(\Rightarrow A=-\frac{5}{2}\)
Cách 2 :
\(=\left(\frac{36}{6}-\frac{4}{6}+\frac{3}{6}\right)-\left(\frac{30}{6}+\frac{10}{6}-\frac{9}{6}\right)-\left(\frac{18}{6}-\frac{14}{6}+\frac{15}{6}\right)\)
\(=\frac{35}{6}-\frac{31}{6}-\frac{19}{6}\)
\(=-\frac{15}{6}\)
\(=-\frac{5}{2}\)
~
a, \(\frac{\left(\frac{1}{9}\right)^6\cdot\left(\frac{3}{8}\right)^7}{\left(\frac{1}{3}\right)^{13}\cdot\left(\frac{1}{2}\right)^{22}.3^6}\)
\(=\frac{\left(\frac{1}{\left(3^2\right)^6}\right)\cdot\left(\frac{1}{2}\cdot\frac{1}{2}\cdot\frac{1}{2}\cdot3\right)^7}{\left(\frac{1}{3}\right)^{13}.\left(\frac{1}{2}\right)^{22}.3^6}=\frac{\frac{1}{3^{12}}\cdot\left(\frac{1}{2}\right)^{21}\cdot3^7}{\frac{1}{3^{13}}\cdot\left(\frac{1}{2}\right)^{22}.3^6}\)
\(=\frac{3}{\frac{1}{3}\cdot\frac{1}{2}}=3\div\frac{1}{6}=3.6=18\)
b, Làm tương tự nha bn
A= E387E4837
B = 883433
C = UỲUWFHQWURY48E3947
Cách 1 :
\(M=\left(7-\frac{1}{3}+\frac{3}{4}\right)-\left(6+\frac{2}{3}-\frac{1}{4}\right)\)
\(M=\left(\frac{84}{12}-\frac{4}{12}+\frac{9}{12}\right)-\left(\frac{72}{12}+\frac{8}{12}-\frac{3}{12}\right)\)
\(M=\frac{89}{12}-\frac{77}{12}\)
\(M=\frac{12}{12}\)
\(M=1\)
Cách 2 :
\(M=\left(7-\frac{1}{3}+\frac{3}{4}\right)-\left(6+\frac{2}{3}-\frac{1}{4}\right)\)
\(M=7-\frac{1}{3}+\frac{3}{4}-6-\frac{2}{3}+\frac{1}{4}\)
\(M=\left(7-6\right)-\left(\frac{2}{3}+\frac{1}{3}\right)+\left(\frac{3}{4}+\frac{1}{4}\right)\)
\(M=1-1+1\)
\(M=1\)
Cách 1:
\(M=\left(7-\frac{1}{3}+\frac{3}{4}\right)-\left(6+\frac{2}{3}-\frac{1}{4}\right)\)
\(M=\frac{89}{12}-\frac{77}{12}\)
\(M=1\)
Cách 2:
\(M=\left(7-\frac{1}{3}+\frac{3}{4}\right)-\left(6+\frac{2}{3}-\frac{1}{4}\right)\)
\(M=7-\frac{1}{3}+\frac{3}{4}-6-\frac{2}{3}+\frac{1}{4}\)
\(M=\left(7-6\right)-\left(\frac{1}{3}+\frac{2}{3}\right)+\left(\frac{3}{4}+\frac{1}{4}\right)\)
\(M=1-1+1\)
\(M=1\)