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\(M=\frac{1}{1+2}+\frac{1}{1+2+3}+\frac{1}{1+2+3+4}+\frac{1}{1+2+3+4+5}\)
\(M=\frac{1}{\left(1+2\right).2:2}+\frac{1}{\left(1+3\right).3:2}+\frac{1}{\left(1+4\right).4:2}+\frac{1}{\left(1+5\right).5:2}\)
\(M=\frac{2}{2.3}+\frac{2}{3.4}+\frac{2}{4.5}+\frac{2}{5.6}\)
\(M=2.\left(\frac{1}{2.3}+\frac{1}{3.4}+\frac{1}{4.5}+\frac{1}{5.6}\right)\)
\(M=2.\left(\frac{1}{2}-\frac{1}{3}+\frac{1}{3}-\frac{1}{4}+\frac{1}{4}-\frac{1}{5}+\frac{1}{5}-\frac{1}{6}\right)\)
\(M=2.\left(\frac{1}{2}-\frac{1}{6}\right)\)
\(M=2.\frac{1}{2}-2.\frac{1}{6}\)
\(M=1-\frac{1}{3}=\frac{2}{3}\)
3/5x(2/3-1/5:3/5)
=3/4x(2/3-1/3)
=3/4x1/3=1/4
đúng 100%
\(\frac{3}{4}\cdot\left(\frac{2}{3}-\frac{1}{5}:\frac{3}{5}\right)\)
\(=\frac{3}{4}\cdot\left(\frac{2}{3}-\frac{1}{3}\right)\)
\(=\frac{3}{4}\cdot\frac{1}{3}=\frac{1}{4}\)
\(\left(1-\frac{1}{2}\right)x\left(1-\frac{1}{3}\right)x\left(1-\frac{1}{4}\right)x\left(1-\frac{1}{5}\right)x\left(1-\frac{1}{6}\right)\)
\(=\frac{1}{2}.\frac{2}{3}.\frac{3}{4}.\frac{4}{5}.\frac{5}{6}\)
\(=\frac{1.2.3.4.5}{2.3.4.5.6}=\frac{1}{6}\)
=17/6+1/2×13/3-9/4:3/5
=17/6+13/6-9/4×5/3
=17/6+13/6-15/4
=68+52-90/24
=30/24
=5/4
\(2\frac{5}{6}+0,5\times4\frac{1}{3}-2\frac{1}{4}:\frac{3}{5}\)
\(=\frac{17}{6}+\frac{1}{2}\times\frac{13}{3}-\frac{9}{4}:\frac{3}{5}\)
\(=\frac{17}{6}+\frac{13}{6}-\frac{9}{4}\times\frac{5}{3}\)
\(=5-\frac{9\times5}{4\times3}\)
\(=5-\frac{3\times5}{4\times1}\)
\(=5-\frac{15}{4}=\frac{20-15}{4}=\frac{5}{4}\)
\(\frac{3}{4}.8,4+2,8.1\frac{1}{2}\)
\(=\frac{63}{10}+\frac{21}{5}\)
\(=\frac{63}{10}+\frac{42}{10}\)
\(=\frac{63+42}{10}=10,5\)
Trả lời:
\(a,\)\(\frac{3}{4}.8,4+2,8.1\frac{1}{2}\)
\(=0,75.8,4+2,8.1,5\)
\(=6,3+4,2\)
\(=10,5\)
\(b,\)\(\frac{3}{4}.2\frac{3}{9}+45,8.0,07\)
\(=\frac{3}{4}.\frac{7}{3}+3,206\)
\(=1,75+3,206\)
\(=4,956\)
Hok tốt!
Good girl