2,4x0,25+5,6:4+2x1/4
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1 + 1 : 2 x 1 + 5 x 6 - 4
=1 + 1 : 2 + 30 - 4
= 1 + 0,5 + 30 - 4
= 1,5 + 28
= 29,5
\(\frac{3}{2}X\frac{1}{3}+\frac{8}{5}:4\)
= \(\frac{1}{2}+\frac{8}{5}X\frac{1}{4}\)
= \(\frac{1}{2}+\frac{2}{5}\)
\(=\frac{5}{10}+\frac{4}{10}\)
\(=\frac{9}{10}\)
7,7 x 0,25 - 0,1 + 2,4 x 0,25
= ( 7,7 + 2,4 ) x 0,25 - 0,1
= 10,1 x 0,25 - 0,1
= 2,525 - 0,1
= 2,425
a: =5-7/19
=95/19-7/19
=88/19
b: =1/2(3/4+1/4)=1/2
c: =26/7(11/3-8/3)
=26/7
x + 1/2 x 1/3 = 3/4
x + 1/6 = 3/4
x = 3/4 - 1/6
x = 7/12
1/2x1/3+1/3-1/4+1/4x1/5
= 1/2-1/3+1/3-1/4+1/4-1/5
=1/2-1/5
=3/10. (1/2x1/3= 1/2x3)
1/2x1/3+1/3-1/4+1/4x1/5 = 1/2-1/3+1/3-1/4+1/4-1/5 =1/2-1/5 =3/10. (1/2x1/3= 1/2x3)
`1/5xx1/2:3/10`
`=1/10xx10/3`
`=1/3`
`1/2xx1/3:1/4`
`=1/6xx4/1`
`=2/3`
a) \(\dfrac{1}{5}\times\dfrac{1}{2}:\dfrac{3}{10}=\dfrac{1}{5}\times\dfrac{1}{2}\times\dfrac{10}{3}=\dfrac{1\times1\times10}{5\times2\times3}=\dfrac{10}{30}=\dfrac{1}{3}\)
b) \(\dfrac{1}{2}\times\dfrac{1}{3}:\dfrac{1}{4}=\dfrac{1}{2}\times\dfrac{1}{3}\times4=\dfrac{1\times1\times4}{2\times3}=\dfrac{4}{6}=\dfrac{2}{3}\)
\(\frac{1}{1}\cdot\frac{1}{2}+\frac{1}{2}\cdot\frac{1}{3}+\frac{1}{3}\cdot\frac{1}{4}+...+\frac{1}{79}\cdot\frac{1}{80}\)
\(=\frac{1}{1\cdot2}+\frac{1}{2\cdot3}+\frac{1}{3\cdot4}+...+\frac{1}{79\cdot80}\)
\(=\frac{1}{1}-\frac{1}{2}+\frac{1}{2}-\frac{1}{3}+\frac{1}{3}+...+\frac{1}{79}-\frac{1}{80}\)
\(=1-\frac{1}{80}\)
\(=\frac{79}{80}\)