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(10+20)+(2+8)+(4+6)=30+10+10
=50
1/3+1/6+4/3+2/6+2/3+5/6
=(1/3+4/3+2/3)+(1/6+2/6+5/6)
=7/3+8/6=7/3+4/3=11/3
`1/2+2/4+3/6+4/8+5/10+6/12`
`=1/2+1/2+1/2+1/2+1/2+1/2`
`=1/2*6=3`
`1/3+1/4+1/5+8/10+20/15+20/30`
`=(1/3+1/4)+(1/5+4/5)+(4/3+2/3)`
`=7/12+1+2`
`=7/12+3=43/12`
\(\dfrac{1}{2}+\dfrac{2}{4}+\dfrac{3}{6}+\dfrac{4}{8}+\dfrac{5}{10}+\dfrac{6}{12}\)
\(=\dfrac{1}{2}+\dfrac{1}{2}+\dfrac{1}{2}+\dfrac{1}{2}+\dfrac{1}{2}+\dfrac{1}{2}\)
\(=\dfrac{1}{2}\times6=3\)
\(------\)
\(\dfrac{1}{3}+\dfrac{1}{4}+\dfrac{1}{5}+\dfrac{8}{10}+\dfrac{20}{15}+\dfrac{20}{30}\)
\(=\dfrac{1}{3}+\dfrac{1}{4}+\dfrac{1}{5}+\dfrac{4}{5}+\dfrac{4}{3}+\dfrac{2}{3}\)
\(=\left(\dfrac{1}{3}+\dfrac{4}{3}+\dfrac{2}{3}\right)+\left(\dfrac{1}{5}+\dfrac{4}{5}\right)+\dfrac{1}{4}\)
\(=\dfrac{7}{3}+1+\dfrac{1}{4}\)
\(=\dfrac{28}{12}+\dfrac{12}{12}+\dfrac{3}{12}\)
\(=\dfrac{43}{12}\)
b)1/2*2/3*3/4*4/5*5/6*6/7*7/8*8/9*9/10
=1x2x3x4x5x6x7x8x9
2x3x4x5x6x7x8x9x10
= 1
10
a, = \(\dfrac{3}{4}\)x\(\dfrac{41}{24}\) = \(\dfrac{41}{32}\)
b, = \(\dfrac{1}{11}\) : \(\dfrac{1}{42}\) - \(\dfrac{20}{11}\) = \(\dfrac{42}{11}\) - \(\dfrac{20}{11}\) = \(\dfrac{22}{11}\) = 2
c, = \(\dfrac{26}{7}\) x 3 : \(\dfrac{1}{3}\) = \(\dfrac{78}{7}\) : \(\dfrac{1}{3}\) = \(\dfrac{234}{7}\)
Học tốt nhá
\(\frac{1}{2}+\frac{2}{4}+\frac{3}{6}+\frac{4}{8}+\frac{5}{10}+\frac{6}{12}+\frac{7}{14}+\frac{8}{16}+\frac{9}{18}+\frac{10}{20}\)
\(=\frac{1}{2}+\frac{1}{2}+\frac{1}{2}+\frac{1}{2}+\frac{1}{2}+\frac{1}{2}+\frac{1}{2}+\frac{1}{2}+\frac{1}{2}+\frac{1}{2}\)
\(=\frac{1}{2}\times10\)
\(=\frac{10}{2}\)
\(=5\)
\(\frac{1}{2}\)+ \(\frac{2}{4}\)+ \(\frac{3}{6}\)+ \(\frac{4}{8}\)+ \(\frac{5}{10}\)+ \(\frac{6}{12}\)+ \(\frac{7}{14}\)+ \(\frac{8}{16}\)+ \(\frac{9}{18}\)+ \(\frac{10}{20}\)
= \(\frac{1}{2}\)+ \(\frac{1}{2}\)+ \(\frac{1}{2}\)+ \(\frac{1}{2}\)+ \(\frac{1}{2}\)+ \(\frac{1}{2}\)+ \(\frac{1}{2}\)+ \(\frac{1}{2}\)+ \(\frac{1}{2}\)+ \(\frac{1}{2}\)
= \(\frac{1}{2}\)x 10
= 5
a: =>3/8x6/3<x<20/21x21/4
=>3/4<x<5
hay \(x\in\left\{1;2;3;4\right\}\)
b: =>56/42<x<11/2
=>4/3<x<11/2
nên \(x\in\left\{2;3;4;5\right\}\)
a: =>3/8x6/3<x<20/21x21/4
=>3/4<x<5
hay \(x\in\left\{1;2;3;4\right\}\)
b: =>56/42<x<11/2
=>4/3<x<11/2
nên \(x\in\left\{2;3;4;5\right\}\)