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Bài 1:
a; (\(\dfrac{1}{4}\)\(x\) - \(\dfrac{1}{8}\)) x \(\dfrac{3}{4}\) = \(\dfrac{1}{4}\)
\(\dfrac{1}{4}x\) - \(\dfrac{1}{8}\) = \(\dfrac{1}{4}\) : \(\dfrac{3}{4}\)
\(\dfrac{1}{4}\)\(x\) - \(\dfrac{1}{8}\) = \(\dfrac{1}{4}\) x \(\dfrac{4}{3}\)
\(\dfrac{1}{4}x\) - \(\dfrac{1}{8}\) = \(\dfrac{1}{3}\)
\(\dfrac{1}{4}x\) = \(\dfrac{1}{3}\) + \(\dfrac{1}{8}\)
\(\dfrac{1}{4}\) \(x\)= \(\dfrac{8}{24}\) + \(\dfrac{11}{24}\)
\(\dfrac{1}{4}x=\dfrac{11}{24}\)
\(x=\dfrac{11}{24}:\dfrac{1}{4}\)
\(x=\dfrac{11}{24}\times4\)
\(x=\dfrac{11}{6}\)
b; \(\dfrac{12}{5}:x\) = \(\dfrac{14}{3}\) x \(\dfrac{4}{7}\)
\(\dfrac{12}{5}\) : \(x\) = \(\dfrac{8}{3}\)
\(x\) = \(\dfrac{12}{5}\) : \(\dfrac{8}{3}\)
\(x\) = \(\dfrac{12}{5}\) x \(\dfrac{3}{8}\)
\(x\) = \(\dfrac{9}{10}\)
a) 4/9.x=25/18:2/3
4/9.x=25/18.3/2
4/9.x=75/36
x=75/36:4/9
x=75/36x4/9
x=675/144
b)x:4/5=25/8:5/4
x:4/5=25/8x4/5
x:4/5=100/40
x:4/5=5/2
x=5/2x4/5
x=20/10
x=2/1=2
c)22/5:x=44/5:5/2
22/5:x=44/5x2/5
22/5:x=88/25
x=88/25:22/5
x=88/25x22/5
x=440/550
x=4/5
h nk
\(x\) \(\times\) \(\dfrac{4}{5}\) = 15
\(x\) = 15 : \(\dfrac{4}{5}\)
\(x\) = \(\dfrac{75}{4}\)
\(\dfrac{12}{25}\) \(\times\) \(x\) = \(\dfrac{4}{10}\)
\(x\) = \(\dfrac{4}{10}\) : \(\dfrac{12}{25}\)
\(x\) = \(\dfrac{5}{6}\)
a;
c; \(\dfrac{1}{10}\) + \(\dfrac{4}{20}\) + \(\dfrac{9}{30}\)+\(\dfrac{16}{40}+\dfrac{25}{50}+\dfrac{36}{60}+\dfrac{49}{70}+\dfrac{64}{80}+\dfrac{81}{90}\)
= \(\dfrac{1}{10}+\dfrac{2}{10}+\dfrac{3}{10}+\dfrac{4}{10}+\dfrac{5}{10}+\dfrac{6}{10}+\dfrac{7}{10}+\dfrac{8}{10}+\dfrac{9}{10}\)
= \(\dfrac{1+2+3+4+5+6+7+8+9}{10}\)
= \(\dfrac{\left(1+9\right)+\left(2+8\right)+\left(3+7\right)+\left(4+6\right)+5}{10}\)
= \(\dfrac{10+10+10+10+5}{10}\)
= \(\dfrac{\left(10+10+10+10\right)+5}{10}\)
= \(\dfrac{10\times4+5}{10}\)
= \(\dfrac{45}{10}\)
= \(\dfrac{9}{2}\)
a: 2h15'-48p=135p-48p=87p
b: =3 năm 16 tháng-2 năm 10 tháng=1 năm 6 tháng
c: =520 năm-335 năm=185 năm
d: =5h12'-2h5'=3h7'
e: =96p200s=99p20s
f: =48h120p=50h
g: =105p147s=107p27s
h: =60 ngày 75h
=63 ngày 3 giờ
i: 28 ngày 36 giờ:4
=7 ngày 9 giờ
j:
24,12p:6=4,02p
\(6-2\left(x-1\right)=4\)
\(\Rightarrow2\left(x-1\right)=6-4\)
\(\Rightarrow2\left(x-1\right)=2\)
\(\Rightarrow x-1=1\)
\(\Rightarrow x=1+1=2\)
________________
\(2\cdot\left(x-2\right)+1=7\)
\(\Rightarrow2\cdot\left(x-2\right)=7-1\)
\(\Rightarrow2\cdot\left(x-2\right)=6\)
\(\Rightarrow x-2=3\)
\(\Rightarrow x=3+2=5\)
_______________
\(\left(2\cdot x-3\right)+4=9\)
\(\Rightarrow2\cdot x-3=5\)
\(\Rightarrow2\cdot x=3+5\)
\(\Rightarrow2\cdot x=8\)
\(\Rightarrow x=\dfrac{8}{2}=4\)
________________
\(\left(3\cdot x-2\right)-1=3\)
\(\Rightarrow3\cdot x-2=3+1\)
\(\Rightarrow3\cdot x-2=4\)
\(\Rightarrow3\cdot x=6\)
\(\Rightarrow x=\dfrac{6}{3}=2\)
a: =>2(x-1)=2
=>x-1=1
=>x=2
b: =>2(x-2)=6
=>x-2=3
=>x=5
c; =>2x-3=5
=>2x=8
=>x=4
d: =>3x-2=4
=>3x=6
=>x=2
e: =>2(6-x)=4
=>6-x=2
=>x=4
f: =>x-2=5
=>x=7
g: =>10-2x=4
=>2x=6
=>x=3
h: =>2x+4=3
=>2x=-1
=>x=-1/2
j: =>x+2=12
=>x=10
l: =>2x+3=3
=>2x=0
=>x=0
a, 1727 + [ 6993 : 111 + ( 848 - 95 ) ] x 4 - 2
= 1727 + [ 63 + 753 ] x 4 - 2
= 1727 + 816 x 4 - 2
= 1727 + 3264 - 2
= 4991 - 2
= 4989
b, 75/100 + 18/21 + 19/32 + 1/4 + 3/21 + 13/32
= 75/100 + 1/4 + ( 18/21 + 3/21 ) + ( 19/32 + 13/32 )
= 75/100 + 25/100 + 21/21 + 32/32
= 100/100 + 1 + 1
= 1 + 1 + 1 = 3
c, 4 2/5 + 5 6/9 + 2 3/4 + 3/5 + 1/3 + 1/4
= ( 4 2/5 + 3/5 ) + ( 2 3/4 + 1/4 ) + 5 6/9 + 1/3
= 5 + 3 + 5 6/9 + 3/9
= 5 + 3 + 6
= 8 + 6 = 14
d, 3/4 + 25/36 - ( 4/9 + 13/18 + 1/72 )
= 27/36 + 25/36 - ( 32/72 + 52/72 + 1/72 )
= 52/36 - ( 84/72 + 1/72 )
= 52/36 - 85/72
= 104/72 - 85/72
= 19/72
2 2/5 - 4/5 :(4/3 - x)=36/25
12/5-4/5 :(4/3-x)=36/25
4/5 : (4/3-x)=12/5-36/25=24/25
ĐK: x khác 4/3:
=> 4/3-x=4/5.25/24=5/6
=> x=4/3-5/6=1/2
x=1/2