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\(\dfrac{7}{19}x\dfrac{8}{23}+\dfrac{7}{19}x\dfrac{15}{23}+1\dfrac{7}{19}\)
= \(\dfrac{7}{19}x\left(\dfrac{8}{23}+\dfrac{15}{23}\right)+1+\dfrac{7}{19}\)
=\(\dfrac{7}{19}x1+1+\dfrac{7}{19}\)
= \(\dfrac{7}{19}+1+\dfrac{7}{19}=1\dfrac{14}{19}\) = \(\dfrac{33}{19}\)
\(\dfrac{75}{100}+\dfrac{18}{21}+\dfrac{49}{32}+\dfrac{1}{4}+\dfrac{3}{21}-\dfrac{17}{32}\)
= \(\dfrac{3}{4}+\dfrac{6}{7}+\dfrac{49}{32}+\dfrac{1}{4}+\dfrac{1}{7}-\dfrac{17}{32}\)
= \(\left(\dfrac{3}{4}+\dfrac{1}{4}\right)+\left(\dfrac{6}{7}+\dfrac{1}{7}\right)+\left(\dfrac{49}{32}-\dfrac{17}{32}\right)\)
= 1 + 1 + 1 = 3
\(\dfrac{8}{9}x\dfrac{15}{16}x\dfrac{24}{25}x\dfrac{35}{36}x\dfrac{48}{49}x\dfrac{63}{64}\)
= \(\dfrac{3}{4}\) *Câu này bạn tự sử dụng gạch nhé!
`1,`
`a,`
`7/19 \times 8/23 + 7/19 \times 15/23 + 1 7/19`
`= 7/19 \times 8/23 + 7/19 \times 15/23 + 1 + 7/19`
`= 7/19 \times (8/23 + 15/23 + 1) + 1`
`= 7/19 \times 2 + 1`
`=14/19 + 1`
`= 33/19`
`b,`
`75/100 + 18/21 + 49/32 + 1/4 + 3/21 - 17/32`
`= 75/100 + (18/21 + 3/21) + (49/32 - 17/32) + 1/4`
`= 0,75 + 1 + 1 + 0,25`
`= (0,75 + 0,25) + 1 + 1`
`= 1+1+1=3`
`c,`
`8/9 \times 15/16 \times 24/25 \times 35/36 \times 48/49 \times 63/64`
`=` \(\dfrac{2\times3}{3\times3}\times\dfrac{3\times5}{4\times4}\times\dfrac{3\times4\times2}{5\times5}\times\dfrac{5\times7}{6\times6}\times\dfrac{6\times8}{7\times7}\times\dfrac{7\times9}{8\times8}\)
`= 3/4` (bạn sử dụng gạch, rút gọn các số là được nhé).
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a) 19993 x 19997
=19993 x 19995 +19993 x 2
19995 x 19995
=19993 x 19995 +19995 x 2
vì 19995 x 2 > 19993 x 2 nên 19993 x 19997 < 19995 x 19995
b)53 x 35 -18 = 53 x 34 -18 + 53
=53 x 34 +(53-18)
=53 x 34 + 35
=> 53 x 35 -18 = 53 x 34 + 35
chúc bạn học tốt nha
I don't now !
very easy
you can do
...................
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1,35 : x : 5 = 3
( 1,35 : 5 ) : x = 3
0,27 : x = 3
x = 0,27 : 3
x = 0,09
1,35 : x x 5 = 3
1,35 : x = 3 : 5
1,35 : x = 0,6
x = 1,35 : 0,6
x = 2,25
x + x : 0,2 = 1,35
x * 1 + x * 5 = 1,35
x * ( 1 + 5 ) = 1,35
x * 6 = 1,35
x = 1,35 : 6
x = 0,225
hok tốt nha ^_^
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\(x+x:0.2=1.35\)
\(x+x:\frac{1}{5}=1.35\)
\(x+5x=1.35\)
\(6x=1.35\)
\(x=1.35:6\)
\(x=0.225\)
![](https://rs.olm.vn/images/avt/0.png?1311)
X + X : 0,2 = 1,35
X x 1 + X x 5 = 1,35
X x ( 1 + 5 ) = 1,35
X x 6 = 1,35
X = 1,35 : 6
X = 0,225
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x=2