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\(x-\frac{3}{5}=1\div3\)
\(x-\frac{3}{5}=\frac{1}{3}\)
\(x=\frac{1}{3}+\frac{3}{5}=\frac{14}{15}\)
Chắc x 1/6 = 5 : 4 là phép nhân
\(x\times\frac{1}{6}=5\div4\)
\(x\times\frac{1}{6}=\frac{5}{4}\)
\(x=\frac{5}{4}\div\frac{1}{6}\)
\(x=\frac{15}{2}\)
x-3/5=1/3
x=1/3+3/5
x=14/15
x.1/6=5/4
x=5/4:1/6
x=5/4x6
x=15/2
a) \(\frac{3}{16}+\frac{4}{15}+\frac{5}{16}+\frac{1}{15}\)
\(=\left(\frac{3}{16}+\frac{5}{16}\right)+\left(\frac{4}{15}+\frac{1}{15}\right)\)
\(=\frac{1}{2}+\frac{1}{3}\)
\(=\frac{5}{6}\)
b) \(\frac{6}{7}\times\frac{8}{15}\times\frac{7}{6}\times\frac{15}{16}\)
\(=\left(\frac{6}{7}\times\frac{7}{6}\right)\times\left(\frac{8}{15}\times\frac{15}{16}\right)\)
\(=1\times\frac{1}{2}=\frac{1}{2}\)
c) \(\frac{19}{20}\times\frac{13}{21}+\frac{9}{20}\times\frac{8}{21}\)
\(=\frac{19\times13}{20\times21}+\frac{9\times8}{20\times21}\)
\(=\frac{247}{420}+\frac{72}{420}\)
\(=\frac{319}{420}\)
12/20=6/10=3/5
24/36=8/12=
3/4=9/12=12/16=15/20
2/5=4/10
12/30=4/10
72/45=8/5
1/4=7/28
a)
(1/3-1/5)x1/4 = 1/3x1/4-1/5x1/4=1/12-1/20=1/30
(1/3-1/5)x1/4 = 2/15x1/4=1/30
b)
2/5 x 3/7 + 2/5 x 4/7= 6/35 + 8/35 = 14/35 = 2/5
2/5 x 3/7 + 2/5 x 4/7= (3/7+4/7) x 2/5 = 1 x 2/5 = 2/5
TK :
978 : ( 7 × x - 18 ) - 216 = 2 + 4 + 6 + ..... + 20
978 : ( 7 × x - 18 ) - 216 = (20 + 2) x [ (20 - 2) : 2 + 1] : 2
978 : ( 7 × x - 18 ) - 216 = 22 x [ 18 : 2 + 1] : 2
978 : ( 7 × x - 18 ) - 216 = 22 x [ 9 + 1] : 2
978 : ( 7 × x - 18 ) - 216 = 22 x 10 :2
978 : ( 7 × x - 18 ) - 216 = 220 : 2
978 : ( 7 × x - 18 ) - 216 = 110
978 : ( 7 × x - 18 ) = 110 + 216
978 : ( 7 × x - 18 ) = 326
7 × x - 18 = 978 : 326
7 × x - 18 = 3
7 × x = 3 + 18
7 × x = 21
x = 21 : 7
x = 3
ta có : `2 + 4 + 6 + ..... + 20`
số số hạng là : `(20-2):2+1= 10`
tổng là : `(20+2) xx 10 :2=110`
`978 : ( 7 × x - 18 ) - 216 = 2 + 4 + 6 + ..... + 20`
`978 : ( 7 × x - 18 ) - 216 =110`
`978 : ( 7 × x - 18 )=110+216`
`978 : ( 7 × x - 18 )=326`
`7 × x - 18=978 :326`
`7 × x - 18=3`
`7 xx x=3+18`
`7 xx x=21`
`x=21:7`
`x=3`
vậy `x=3`